As soon as ANY other platform has even half the functionality and features that Steam has, then this doofus' argument might hold water. Show me one other storefront with:
Something akin to Workshop.
Native VR support (not just asking someone else's storefront to do it for them).

How about the ability to see games that were previously installed onto a drive and re-integrating them? Only Battle.net does that one, ALL the other stores want to re-download massive games rather than just do a check of the data that's already there.

That's ignoring a warehouse of other features I personally never use. Does any other storefront have a store interface mode that's designed to work with a controller (BigScreen mode)? Where's your fucking forums at, Epic?

Steam may charge the (actually standard) 30% instead of Epic's varying rates, but Epic's app and storefront is a fucking JOKE.