Do not automatically update games was the setting, and that setting never did anything else but exactly what it said. It didn't start the updates automatically when they arrived, it deferred them till you started the game.

That's how it was as far back as at *least* 2011 and the supposed 'change' (at least most) people refer to didn't happen till 2014.

Unless you are aware of an older change in the system?

2013 thread complaining that "Do not update" still updates the game.
2012 thread asking how to keep games not updated, answer was edited in 2014 though.

Not sure I want to go looking at this any more though, but should be a good start for someone who actually recalls this option.

No it did not. I would regularly avoid certain updates *and* run the game at will. Updates did not occur at startup as some here have claimed. I can say this for a fact. It was particularly noteworthy as, after that update to how that system worked, I could no longer opt out of updates and was forced to update whether I wanted to or not. Obviously the benefits to Valve proper superseded the benefits to the consumer being able to control what they purchase, but what else is new. These are the flipside aspects of digital distribution.

The confusion for many seems to be the difference between "check for updates on start" and actually forcing the player to download and install the update. The former option allowed one to just not update, despite it informing the player. EG - Me holding a sign that I'm going to hit you with a bat vs me actually just hitting you with a bat.

Source 1 (there are more if I need to Hiroshima this argument) : http://gaming.stackexchange.com/questions/81470/is-there-any-way-to-stop-steam-downloading-updates
See my post above.

The one I linked above. See Ramhound's reply two posts below the second picture. That setting would still auto-update.
Do Hiroshima the argument, I always enjoy being proven wrong.
Still, thank you for replying.

Furthermore I continued my studies. Yes, I know I wiped Steam off the Windows XP VM. My siblings kept pestering me about getting it back recently, mostly for Team Fortress 2 and Garry's Mod shenanigans...so I decided to grant their wish and install them Steam on the desktop PC that they use. Now halt for a sec.

Somehow, installing a game would FREEZE the client temporarily before it comes back with an installer window. This behavior weirded me out, considering that it performed better on a VM with worse specs.
Desktop vs. virtual machine:

2.8GHz dual core vs. 1GHz dual core
4GBs RAM vs 1GBs RAM
AMD Radeon 5450 vs. Whatever Virtualbox uses for graphics
Windows 10 vs. Windows XP

I can't even. Steam on a VM performed better than an actual machine with better specs. Latest version and all. What's the deal...I don't care, that'll be my siblings' problem.

I then tried Family View Sharing to limit them off from the Sakura VNs which are adult-flavored and all...it is good it lets me fine tune how they can access Steam's corners such as the store and all, but somehow it always felt off when...the settings suddenly vanish. Then I remember family view is on and I'd have to take it down. And when I do so for some reason, I always become online to my friends...no questions asked.

Granted, Family View worked in theory as long as I didn't download the Sakura games and enter download view to see them being downloaded, and I honestly don't know if clicking Play would still launch it despite supposedly being inaccessible. However, the Family View button is a total eyesore...badly designed, very. Steam needs an interface update if not a business stance update...