Steam sells an ecosystem, really. To developers they're selling a CDN with integrated cloud save, cross-platform multiplayer, community management software, Steam Workshop tooling and a designated support channel. To users, they're selling a well-designed interface with the ability to modify and add games to their heart's content. If either side is upset, they can avoid Steam altogether and still distribute their app as freely as their OEM allows.

I use Steam because they care about Open Source. Not many "ecosystem" hustlers ever give back to the community they take from, but Valve does, and I appreciate the work they do as a non-Windows user. Were it not for their efforts in DXVK I wouldn't be able to play Indie games at all, Valve-published or not. The "community attitude of Gabe worship" largely springs from the fact that the guy still answers emails, manages his business, and keeps Valve private to avoid shareholder intervention. A lot of the current Valve "spirit" is associated with Gabe Newell's dedication to avoiding venture capital and supporting Open Source appropos of nothing.