I don’t personally think it’s because of that. Sure, federation as a concept outside of email has a bit of a messaging problem for explaining it to newbies, but… everyone uses email, and knows how that works. This is identical, just with it being posts instead of emails. Users aren’t averse to federation, in concept or practice.
Bluesky was directly created as a very close clone of Twitter’s UI, co-governed and subsequently pushed by the founder of Twitter himself, who will obviously have more reach than randoms promoting something like Mastodon, and, in my opinion, kind of just had better branding.
“Bluesky” feels like a breath of fresh air, while “Mastodon” just sounds like… well, a Mastodon, whatever that makes the average person think of at first.
So when you compare Bluesky, with a familiar UI, nice name, and consistent branding, not to mention algorithms, which Mastodon lacks, all funded by large sums of money, to Mastodon, with unfamiliar branding, minimal funding, and substantially less reach from promoters, which one will win out, regardless of the technology involved?
It actually does exist, at least on Mastodon, but is still very janky (e.g. old posts aren’t moved over due to “technical limitations”)
Automatically makes people unfollow your old account and re-follow your new account, then makes your old instance’s link redirect to your new instance’s one.