[Ekaros]

What about Amazon? Or any other dominant player in any market?

Steam does not come pre-installed on nearly every device unlike Apple's and Googles offering. Future Steam Deck not withstanding, but that will be miniscule player.

They don't prevent any other store from operating. So I don't see how they are comparable to anything Google or Apple does. Windows Store might qualify if they forced themselves on Windows in same way. But certainly Steam is entirely different.

[fragileone]

Even the Steam Deck is just a Arch Linux device, so you can install any games store like Epic or Origin or GOG on there if you want.

Unlike the Google Play Store which gets special access to APIs that other app stores cannot use.