Fediverse platforms are not in competition with each other. In fact, it's more like symbiosis. There's no problem with having 15 or even 100 fediverse platforms.

Why do you need a culture shift if anyone can just pick whatever platform they personally prefer? If you want a certain cultural approach, then feel free to use a fediverse platform with that approach, but there's no need for anyone else to follow the same choice, unless they want to.