Comment by jeroenhd

The difference between Valve and the other app stores with an actual user base (i.e. not Microsoft's Windows Store) is that PC gaming isn't tied to a single app store.

To be fair, neither is Android, but Steam actually gets real competition from GOG. The Amazon App Store was never really popular and the Epic Store doesn't seem to contain anything interesting if you're not playing one or two popular Epic games. Small projects can use itch.io. Large companies build their own launchers.

With the Steam Deck and now the upcoming new Steam hardware, that may change, depending on how hard Valve makes it to integrate with Steam's UI. Right now, Heroic works fine, from desktop mode, but if a company like GOG would like to actually take part in SteamOS, they'd need some kind of integration capability.

So far, nobody but Valve seems to have even considered supporting Steam and Linux' market share is small enough that it barely affects the gaming market, but if their Steam Machine explodes in popularity and they make mistakes, they can end up on many people's bad side just as well.