It’s not an unreasonable cut, the reason they’re successful is they provide such a good service that any time someone thinks “well I don’t wanna pay that 30% cut, I’ll just do it myself” they fail. That 30% is for all the million features that benefit both devs and players which nobody wants to build an alternative for.

I mean it is unreasonable in that this sort of thing should be publicly owned and operated infrastructure, rather than a digital walled garden for the master who owns it to make obscene profits from

part of what you describe is people “not wanting to build” an alternative, but part of it is also that 1) building an alternative means dealing with breaking into what is effectively a monopoly, and you can see how successful that’s been for Origin/Epic/whatever, who seem to be slowly gaining steam but that’s only after years of literally giving away free $60 games just to get people to download their launcher and 2) having alternatives ultimately degrades the quality for everyone because instead of having one integrated service you now have all these competitors with all their varying (or missing) features and just the general hassle of having to keep up with what’s on any of them