Maybe it doesn't bear mentioning that Epic Games takes 12%, since they're no less fiefly. But Itch.io, while not collectively owned, is definitely both gamer- and developer-friendly in ways Steam and its ilk aren't, and they let the seller set the revenue share. Is that insufficient? If so, why?

If their position is that private ownership makes Itch a doomed venture, or at least not a fulsome way forward, then I can follow that (even if I don't agree). This gets to exactly the sorts of stuff SE seems to be wrestling with: Building democracy and equanimity into existing business structures.