One thing is for sure: users want to see relevant high quality information, not spam. And there is also a huge gray area of not-so-obvious spam.
The fediverse has a superior tool to combat spam, by unfederating instances that produce it.
So I do think that the fediverse will kind of win out. I can also see how there will be clusters within the fediverse with different norms.
Some clusters will not allow any hate speech, others will become a magnet for extremists. And the same kind of fractures will happen to other controversial topics.