And yet most posts people end with saying something similiar to "I'll just wait 2 years and get it for half price on Steam" which is explicit support for the Valve monopoly.
Not really, but I see what you mean. It’s a thorny question, because it is actually pretty practical to use a single service to buy all your games, particularly for those who use the social features, compared to trying to keep track of your friends regardless of if they play on Steam, battle.net, Origin, GoG, Epic game store,....
While you may support multiple competitors in principle, for a given individual it’s a pain in the ass.
I use Steam, and I support GoG because I like what they do. Beyond that though, it’s just different megacorps wanting a piece of my pie for no apparent benefit to me as an individual. I have to use battle.net for Blizzard games, but that doesn’t mean I like having to do so.
If Epic had charged publishers 20%, and then used some of that margin to undercut Steam, nobody would have minded. Not saying they would have been more successful, but they wouldn’t have come off as ”publisher first, consumer second".
If I had started gaming on PC today, I would probably have used GoG as exclusively as possible, but history matters.