I think that an open systems that are universal and interoperable are inherently superior to any walled garden. If people think that the fediverse can’t handle or incorporate large corporate interests then this is a failed experiment and they should just shut it down now. Superior open systems should be able to dominate a free market environments, and people either don’t believe this to be the case, or the fediverse is inferior and will never beat the centralized competitors.
I also hate Facebook but for those reasons I think that Facebook joining the fediverse would actually improve Facebook, not worsen the fediverse.