EGS is used as an example. They don’t charge devs until they earn $1M so you’d think games would release there at least but we now have many many Steam exclusives. It’s gotten to the point where indie games release demos on Itch.io but don’t release full games outside of Steam because they need algorithmic momentum there.
Check out EU DMA and how it impacts gatekeepers like Valve (even if Valve somehow dodged that label, probably because their finances are private).