Tetris is Russian propaganda that teaches children doing good work is pointless as it will just be taken away and you’ll be forced to do it again until you do it half assed.
Walmart and GameStop provide a physical place, that’s it. The Developer sends them the physical product.
Steam provides unlimited downloads, user forums, automatic updates, remote play, user reviews, Steam workshop etc…
None of these other stores provide these things.
Maybe Epic should charge more than 12% and invest that money in improving their client, or at least do that instead of wasting it on exclusivity deals. Then maybe I as a consumer will give a shit about Epic.