That’s not inconsistent. Users can choose to use the Epic store or not. If they choose not to use it, they can’t buy games from that store, just like I can’t buy Trader Joe’s food if I decide to not use the TJ’s store.
Exactly, people are having a hissy fit over exclusive content that has no further price than downloading a free store app. It's like whingeing about driving to another store to get the brand of ice cream that you like. I have no problem with that as long as the device manufacturer doesn't limit me to a single store. Preferably I'd like to be able to choose any store or independent content. More choices, more freedom, more competition.
It is in fact those three things. Different stores compete with each other providing different value, both users and devs having the freedom to choose to support one or the other (or all) based on their personal criteria.