You’re describing how you would compete in a normal competition, but Steam has already had a decade to lock in it’s following. The competition is/was over.

I say that as a Steam user, there’s absolutely nothing a competitor can do to convince me to start buying / keeping my games on a platform outside Steam. Steam just has it all AND that’s where all my existing games already are. No amount of UI/UX improvements will convince me. No amount of sales will convince me because Steam will have the same game. Better cuts to developers doesn’t bring in repeat customers.