They define decentralisation as an even distribution of users? Or did I get that wrong skimming the paper?
This seems arbitrary. Mastodon is a decentralised network, no matter how big Mastodon.social is. Lemmy is equally decentralised, even though there’s a dominant actor.
The other hubs in the network don’t revolve around mastodon.social/lemmy.world. they connect to each other bilaterally - if the central hubs disappeared over night it wouldn’t affect them all that much.
I think the notion that decentralised networks can’t have hubs of varying sizes is plain wrong, and a fundamental misunderstanding of what decentralized means.
The official story is that Meta is worried about being sued by people suddenly seeing their content pushed to some random website without their consent if it’s enabled by default, so they won’t risk enabling it by default. At least not before the fediverse is huge enough that everything you post going everywhere on the internet is the expected behaviour.
Fair enough really. I wouldn’t want to be sued for that either, and they obviously cannot expect Congress to understand… anything.