Tim Sweeney recently mentioned how Steamworks API has become a problem for PC gaming:
https://www.pcgamer.com/epic-games-store-self-publishing
Examples like this prove his point exactly. We're talking about single-player games, but API integration functions as vendor lock-in. Instead of just making a single vendor agnostic version of a game that can be sold on any storefront, functionality such as leaderboards and achivements are 'expected' by customers, so devs plug them in, which makes shipping games to any other store more burdensome on developers and publishers. Those psychologists Valve hired all those years ago did their job well, creating all sorts of obnoxious gimmicks like lootboxes, trading cards, stickers, badges, and achievements to help cement Valve's position.

Likely all the indie sequels that also skipped GOG?

Stuff like Darkest Dungeon 2, Freedom Planet 2, Shadows Over Loathing, Shovel Knight Dig, Slime Rancher 2, Sword of the Stars: The Pit 2, etc.

There are probably several games not coming GOG over low sales. Why bring the game to GOG when Epic and Steam make up 90% of the market.

Honestly, I feel GOG and ZP are going to be nothing more than a hole in the wall kind of store. It won't get better, especially when we have people on forums talking about going back to steam. I don't think DRM free stores will die but will have to accept the fact some games will not be coming.

I pretty much cut steam out completely when it comes to buying games.

One of the reasons why they get so few sales on GOG is because they treat GOG customers like second-class citizens, such as by not giving GOG customers Achievements like they do for their Steam customers.

So they largely have themselves to blame. I'm not gonna pay them to treat me like an unequal second-class citizen with missing features, and I am sure many other customers aren't either.

Also, their games generally have ridiculous prices and discounts that are negligible, for games of theirs that are also very short (i.e. the Shantae games)...which is another reason their low sales on GOG are largely their own fault.

To be fair, GOG isn't anywhere near as bad as Zoom Platform. You are right, however, that the market's too consolidated. We accepted Steam as the only option for so long that it essentially IS the only option to most developers. GOG is making a lot more of an effort, seen the the relatively constant drip of new titles, but we're always going to have to deal with the 800-pound gorilla in the room, something even Epic is having trouble cracking due to entrenched practices, as the article SCPM linked mentions. While I've never cared about achievements, I do agree that the bad discounting and lack of feature parity are an issue. I'd had hope that Galaxy would alleviate games coming out here without multiplayer, and it did for a while, but it seems the old ways returned. HOPEFULLY Epic requiring cross-play will help the issue of overly-lazy developers focusing on Steam to the exclusion of everyone else, but I'm not holding my breath.

Ever feel like the whole industry is just pushing you out? I've felt that way sometimes...

Honestly I don't see anything new under the sun here.

Ever since I started buying on this store that I always saw GOG as a place to buy "second opportunity" games. I'm not trying to insult the store in any way. It's just the way I feel it: a place to buy DRM-free games which publishers and the mass of gamers no longer remember or see as relevant.

If one looks at the history of the store, we can see a pattern of small-time publishers which - after getting public renown and becoming famous - start to forget GOG and focus only on steam, where the big $$$ is.
Some years later - when these new games start to get buried under a growing pile of indie, AA or AAA games, then the dev or the publisher finally remembers to sell them on GOG or zoom where they can finally land some fresh bucks.

It's also no coincidence that games which flop on steam seem to arrive on GOG rather quickly.

Besides, like SCPM very well pointed out, the gimmicks and "bonuses" created by valve to use on their store and keep gamers addicted to steam biome also makes devs work harder to focus outside the store.
I recognize the importance of steam to the growth of PC market. But I - like others - fear the toxic effect this may cause to the market in the long run. Perhaps even steam itself may one day suffer the consequences of its own "gaming monopoly".
Time will tell...

EDIT:
It also doesn't help that almost everything on the Western World has gone into "full retard mode". And gaming is one of the most obvious cases since it's such a popular hobby.
Don't expect much logic or sanity from anything from now on.

EDIT 2:
I've noticed that even the "gaming press" seems to be in crisis nowadays. Some years ago regular articles or newsposts from PC Gamer or RPS would gather several dozens of comments. Nowadays most articles struggle to gather even half-a-dozen comments. It seems that gamers are really changing their focus.

Well, that should smash some delusions of grandeur that exist in these halls...

Ah, who am I kidding...the usual 120 to 150 people will keep believing that throwing their hissy fits will change the industry.

Normal people don't care about DRM unless it stops their game from working. Even then they only care until it's fixed, and not when the next game comes out.

Normal people like clients and online social features.

Normal people want all their games in one place so they don't have to juggle multiple clients.

So... what can ya do?

The only thing GOG has that could possibly appeal to normal people is making old games work better. Even then, the vast majority of games without severe licensing issues are already here. GOG tried to make a play for Steam market share and it didn't work out, and they wasted a lot of money doing so. It is what it is.

Treat this store like a library of classics, back up their offline installers, then go about your day and accept the world as it is.

The thing is, while people are saying that Steam Workshop is a problem, then why are many of these games selling on places like Itch.io where there's not much of a client or even much in the way of a mod manager? Why isn't GOG using an open source mod management system?

What was the saying again? You miss every dollar you don't sell?

Reminds me of an old Jim Sterling video where he/she(? I don't keep up with them anymore, but something happened and they're trans or non-binary now?) pointed out that big publishers like EA were skipping the middle market where they either go big or put out small budget titles, or otherwise ignoring more niche tastes. To me, GOG fills an important niche where ignoring it is going to lead to bigger problems later on since their releases are fire and forget (in a good way, no DRM to remind you ownership is an illusion). At least some big name YouTubers give GOG a shoutout. Some.

True enough. Hopefully this place doesn't go away and have everyone not interested in Steam going back to the abandonware mines, but considering the gaming industry is intrinsically toxic, I see it as only a matter of time. Gaming is, after all, a luxury, and will likely evaporate once the monopolies start really exerting their power.

My only real solace is that, when contemporary gaming does entirely push me away, I'll have more than enough games to keep me going, and there are plenty of other forms of entertainment out there.

Isn't Itch.io missing a lot games like GOG? I keep hearing people talk about Itch.io but every time I check them out, they seem to not have much. When I do find a game you have to buy it from steam instead of Itch.io

Honestly I would not want GOG filled with all the shovelware that is on Itch.io.

GOG don't force you to download and install a client, before even allowing you to download your games. Do you consider that as a second class citizen? I would rather just download the game itself, without a client, and get on with it.

And if you really want achievements, what's to stop you from thinking them up for yourself? You don't have to rely on a list that somebody else wrote, to enjoy the game.

Nobody has all games in one place, even steam. Steam is missing huge titles from blizzard, league of legends, guild wars 2.etc