There should be case studies about the ineptitude of competing stores. A small handful aside who have found a niche and serve it well (itch.io and GOG come to mind) the other stores just dish out a store front that is under-cooked for what is there and lacking features beyond that and then are surprised when people prefer Steam.

For example I’m not aware of a Workshop style system in any other store, so any game that features community made content will be a better experience on Steam.