So the most-blocked server is only blocked by 4.2% of the servers on the network. This means that, at most, only 4.2% of the admins on fedi use #fediblock, and 95.8% of them ignore #fediblock. Since FSE is the final boss of the #fediblock list, it's safer to say that at least 96.2% of the admins on fedi ignore the list. You could probably do something more thorough, say that you produce a count of instances that block at least half of the instances on the list, and this would get you a more accurate number, but I think it would still be pretty small, maybe two, three dozen.
> Because it could indeed be possible - they've lost a lot of people since the last exodus from twitter
They were never the majority on the network. I have constantly heard, since close to the beginning of FSE, "Everyone is gonna block you!" and it's mostly neurotics (who filter so heavily that they have a distorted view of what represents a majority view; "How could Nixon have won? Nobody I know voted for him.") and people playing the social-pressure game (which gives them an incentive to claim a majority), and that's a long way from "everyone".
There's also that paper about blocking that got passed around a while back. They did some analysis; I disagree with a lot of their proposals, but it's a more thorough treatment than anyone's given #fediblock until now: decentralized_web_moderation.pdf