Mastodon is interoperable, decentralized, operated by a nonprofit, lively, and, ACTUALLY, isn't hard to use. So why is everyone championing Threads as the main Twitter alternative?
Also obscurity, practically none of the content creators or companies I followed on Twitter have moved to Mastodon and getting news from them was the only purpose of that site in the first place (for me).
Which is part of why we should want all the popular social sites to be federated, so that holding the userbase doesn't create an insurmountable monopoly and you can easily move to a better alternative without leaving your friends and content behind
This is why Lemmy (previously Reddit) is hugely more appealing to me than mastodon or twitter. I want sensible discussion and useful information, not to hear what some celebrity or internet persona is thinking about while they take a shit.