I believe GoG at least has a selling point: no DRM, and you can download installers of all their games for backup purposes. Epic has nothing different from Steam, and it's even behind in many areas (natural, since Steam has been in development for far longer). I myself prefer to buy on GoG for the backup and no DRM, given the choice. Epic? Ubisoft? Blizzard? Microsoft? Only for exclusives. But if anyone wants to get some of Steam's cake, they need to develop the tools that Steam has: community tools, Workshop, Steam Play/Link, Market, etc.
I don't think Steam can remove DRM from anything without asking the developers first, and I also think most of them wouldn't want that. Nice words, but they can't promise that.