That's a weirdly lopsided argument. You seem to be saying that competition has failed and will yield a monopoly and the answer is regulation, which will fix the problem the second it gets over having failed at the exact same task.
Again, you're not wrong, you need to course-correct the market through regulatory oversight. But that oversight is meant to both guarantee quality standards and re-enable competition in places where it has dried out.
For the purposes of the conversation we're having, the regulation solution here is to fine or break up Steam so that other players can compete with them, ultimately. Well, and potentially to see if they should cut it out with the CounterStrike loot boxes and whatnot, but that's not what we're debating here.
So I'm not sure what your point is. Sure, eventually in a world where Steam is the only player in PC game distribution someone should step in and fix that problem. But before we get to that, as a user, I am not going to be here cheerleading for Steam to secure its monopoly first.