This whole conversation is about how there is very few options for games where it is financially viable to build content for them as a third party. I am not claiming that other games are not fun, you just can't make a successful business on top of them.
Yes, it's possible to make your own game, but it's also possible to make your own app store. There is value in being able to build on top of successful platforms. These existing app stores can demand a bigger cut than doing things yourself because they bring a lot of value and paying customers to the table.
