The main driving force for enshittification is relentless greed for more profit. So the rules of the system matter, if they can't own the users accounts that changes the possible strategies and likely outcomes.
Of course it's possible that the sabotage the fediverse or that it sabotages itself but the underlying "energy" which feeds it development is different. And that matters.
This is part of the neoliberal propaganda, making people believe that greed does not have an effect on quality or morality of behavior, and of course that governments or non-profit can never be "efficient". But that is mostly baseless.
You totally can create institutions with a different agenda or mandate than profit and it works. Of course they can also be captured or sabotaged.