The other platforms on PC are exactly the same though. If you're against Steam because of this particular aspect, you should be against almost all platforms on PC as well as every console and phone platform. This is how it works on almost every digital media platform. It's not sufficient reason to treat Steam like a monopoly, because in itself it's not anti-competitive behaviour.

It's also not solvable unless you legislate platform agnostic licenses that are valid regardless of platform. Fat chance of that ever happening and I doubt that's actually what you're suggesting.