Can several lesser wounds equate a greater wound or would you simply be able to bruise someone an infinite amount of times without causing any real harm?

Wounds are specific, not cumulable.
But they will add penalties and the more wounds the highest the chance to go in shock or even die due to excees trauma.
This will based on ohysical and mental stats.

So, you could go in shock with 2 serious wounds or 1 crippling or taking 10 bruises.
Think two guys doing a brawl or two guys using swords.

My point is, it makes no sense to complain (like you was doing) about the realism, if the developer doesn't want a realistic game in the first place, and he never promised realism.
That's like complaining that Day of the Tentacle has jokes, and saying the game is junk for not being serious. The developers never wanted a serious game...
While there are certain things which simulate the needs of a human being (the need to eat, sleep, etc), there are other things like magic and wisps. That's the world the developer imagined, he can create anything, he is not limited to what is realistic :)
Minecraft also has hunger bar, and is far from being a realistic game.
Very far.

As said, try UnderRail, or Age of Decadence. Their systems and implementation are un-matched.

Some possible issues that could come up with such a rule system:

1. A combatant could simply refuse to die. As long as the chance to go in shock is less than 100%, it is possible for someone to simply refuse to die, resulting in combat taking a really long time.

2. Penalties, if added enough, could result in a situation where neither participant can hit the other, leading to a situation where the combat can't end. At this point, the only option would be for one participant to flee, and if both have been wounded in the legs (and assuming leg injuries affect movement), that could lead to a problem.

Also, one issue with applying penalties is that it makes it so that, after a while, it is inevitable that one particular side will win. This happens with conventional hit point system when enough participants on once side are killed, but with the penalties, this could happen even before then, creating a situation that is not fun for the losing player.

Another thing is that such a system is more complicated than a simple hit point system.

Incidentally, another related issue can be applied to magic systems; a system like D&D with spell memorization and slots tied to spell level is more complicated than a simple spell point system and also leads to strange behavior (I am out of Cure Light Wounds spells, so why can I still cast Cure Critical Wounds?).

Good points.

1. Eventually you will succumd to shock. An hardier character can resist more, potentially, but will reach the "breaking" point, no matter how lucky he is.

2. Even here it is not possible: attack/defense are active and results are crossed, to give always an outcome.
If everyone is really badly wounded, even if they can hit one other, they will stumble, fumble the weapon or else, giving room to even more interesting action.

Yes, it has it's complexities to implement, but is somethign different from 800 hit ponts.
I'm trying to do my own cRPG on this rules.

You can't run away from having HP. If everyone dies from one bullet it means that we have one HP. In "realistic" system where you die from one sword hit to head but two sword hits to chest it only means that body parts have different HP values. Talking about bruises, light/serious/crippling wounds is just a fancy way of saying that longsword deals 1-8 damage.

That's true.
In games like Contra, you instantly die if your character touches an enemy, projectiles fired by the enemy, or traps.
So it means both P1 and P2 have only 1 HP per live.
It's a game where the health points are invisible, but they are still there.

You could try to avoid HP by making the character immortal, but you would still need to make some weak points, otherwise the game would have no challenge for the player. Talking about RPGs here, I know you don't die in Golf games and they can be challenging.
Planescape Torment has an immortal character, he never dies, but if he suffers too many attacks without healing with items, he will get unconscious and be moved to the mortuary.
Even the protagonist in Torment has health points, but they work a bit different than other games. He can't die, but you could still lose progress, so there is some things for the player to be worried about.

Well, you *do* have the option to pick a fight with the Lady of Pain. She can end you with a thought. And Lothar can put you down for good, too.

One interesting example of an immortal character, though not one that would fit in an RPG, is Wario Land 3.

In Wario Land 3, you can't be killed by enemies. However, if you get hit, either you get knocked back, or you are affected by a status condition. Examples of such conditions include being filled with hot air (you rise upwards until you hit a spike), becoming a zombie (landing on certain platforms will cause you to fall through them), turning into a ball of yarn (causes you to roll uncontrollably until you hit a wall (although some walls can be destroyed in this form), being set on fire (run uncontrollably until you hit water, or a certain amount of time passes, causing you to be engulfed in a flame that can destroy enemies and certain walls), and even becoming a vampire (you can turn into a bat and fly, water and light will cure this condition).

As you can see, this creates a situation where avoiding getting hit, while sometimes necessary, isn't always the best strategy. In fact, sometimes you need to be hit by something in order to progress.

Note that, in boss fights, being hit will turn you into a form that forces you out of the battle, requiring you to start the battle over. (Fortunately, bosses generally have only 3 HP in that game.)

This system could actually work quite well in a puzzle game. (In fact, Wario Land 3 could reasonably be classified as a puzzle platformer because of this mechanic.) On the other hand, I don't see it working well in an RPG.

True, and you can also kill yourself with an special blade made by a (demi?) god.
It doesn't invalidade my point, though. Health points are still present in Torment, but (for the most part) when they reach 0 your character isn't killed.

To be frank, if there's an option to mess with any god or super powerful entity in a game, I don't expect any less than being completely obliterated by it, not even the soul of the character being be spared.

Unless the playable character is a killing machine, of course. Like in God of War games.

I think things get confused between having HP and having some mathematical representation of wounds.
They looks similar until you see them in action.

You can received 10 wounds to head, to die by a sever leg and bloodloss.
That's absolutely different to have 11 hits of 5HP each.

It looks different, but it's the same principle, just more complicated in "realistic" system.

And what are losing all blood, stopping breath or getting beheaded if not the status effects resulting in instant death? They are already present in many games. In Wizardry beheading results in death no matter how much HP you have.

You mean getting hit in the head, but die due to a previous injure which slowly reduces the character HP?
RPG games have various conditions which can inflict damage (apparent to the player or not).
Suddenly seeing a game over screen because your character was poisoned is not that uncommon.
In Fallout 1 for example, after visiting The Glow, a lot of players get killed after being contaminated by radiation.
Explain to me how being dead by radiation or by a bandit melee attacks makes a difference. When your HP goes to zero the result is the same.
Just because the radiation doesn't clearly appears to be reducing your HP, doesn't mean it is not doing basically the same as the bandit.
The only difference I see here, is that you can cure radiation and stop the damage, something you can't do agains a bandit.

You could hide the HP, and make a system where the character dies when he/she loses too much blood.
It's not a radically different thing. Unhurt, hurt, dead. Or if you don't like frustrating players: Unhurt, hurt, almost dead, dead.
You may hide the numbers from health points all you like, numbers are just easier for a player to understand, IMO.
I prefer seeing: Hero 85/100 HP than: Hero is hurt.
Also when an enemy hits the player critically, it's easier to say in numbers, than try to convince the player why he/she received more damage.
"You died, the enemy was Jackie Chan brother, and used a super secret technique called 'Snake-tongue of Blue Dragon' to kick you in the head, making your brain explode. He was waiting the right moment to show you what he learned. I know you had a legendary iron helmet, which you got after 50 hours fighting in a cave, but have you watched Jackie Chan fighting?"
Though that could make a game hilarious.