It seems you don’t know, but we don’t talk about that

TPB is a honeypot now.

-Valve didn't kill ownership it was already dead. DLC has been pulled, and games delisted, as well as games made unplayable by server shutdowns. They just happened to be the platform who told you to your face what you were getting into while everyone else lied and said the game was yours until it wasn't. They also say they'll provide downloads for a time if they ever shut down, but if you want that long term guarantee you're probably better off looking at GOG and some kind of data storage for the installers.

-Origin is shit and I hate EA/Origin exclusives too, but it's basically a launcher for their own games which I understand, but still prefer steam to be included too, so much of the time I avoid EA games (i avoid them for a lot of reasons tbh)

-Battle.net started as a unified launcher for blizzard games, which sort of made sense as they never worked with or were involved with steam, and many of their games were disc based or had its own installer. Subscriptions specifically I don't think existed with steam for a while so that was sort of a complicating factor. Still wish their games were on steam, but it sort of made sense at its inception.

-I don't even use the microsoft store unless forced to, I find it annoying and bleh. They're forcing more games to it and it's shitty too.

-Epic is annoying, but it's a special kind of annoying because for many games early on, they would announce steam as a supported platform, some even sold the game on steam, until they changed to Epic exclusives. I think Fall Guys was one example. The bait and switch really lost them trust with a lot of gamers and you'll find the attitude towards them can be pretty bad because of that history.

Add in that many of the games aren't published by them, they just threw money at the publisher or devs to make their games epic exclusive. This can be good for developers, like an upfront investment, but sucks for gamers who like to keep things somewhat unified in terms of a game library. Especially when you already have to deal with 5 other launchers, another arbitrary one is pretty annoying.

If you're wondering why people want their games on steam, look at the features. Free cloud save backups, a decent amount of free screenshot backups, in game recording is new and pretty neat, achievements, community marketplaces, frequent sales, family sharing, steam workshop for easy integrated modding, discussions and guides for all your games, early access games, built in friends, text chat, voice chat, remote play together, game streaming, etc.

TLDR: It isn't an "oh epic stinky just because" situation. The Epic game store simply doesn't have feature parity, bait and switched gamers multiple times with exclusives after games were advertised as being on steam, and basically survived on throwing money at devs to put their games exclusively on EGS, at the expense of the people who want to play those games on their chosen platform. Doesn't shock me that they don't have a lot of positive PR in the community.