I'm of two minds about this. I don't really hold a super high opinion of Jack Dorsey, but regarding why he left Bluesky I think he actually had a point. It's not really clear what Bluesky actually practically does other than directly compete with Twitter.

The thing that steams my rice personally is that I am friends and acquaintances with a variety of different folks who use social media. I don't think Bluesky would have seen nearly as much adoption if it didn't position itself as having solutions to the inherent problems of centralized social media: the same promises are what propelled growth on Mastodon, too. But see, even though Mastodon is flawed in many ways, it really does solve some of the problems of centralized social media. It lacks some of the theoretical capabilities that Bluesky and AT proto offer, and I absolutely think what Bluesky and AT proto offer on paper is amazing. Censorship resistance! Host your own PDS! Relays keep working when PDSes go down! Sounds good, whereas on Mastodon your identity is tied to where your data is hosted and there's nothing good to do when an instance goes down. However... In practice, none of it matters because indeed, AT proto adoption seems rather unimpressive. The Bluesky app view offering a single URL regardless of where the data is hosted is great, but... In practice, it centralizes all of the moderation for all users. The way Bluesky operates today makes it more like Twitter with extra steps. And knowing some of the moderation woes, I'm not sure I'd categorize Bluesky as unilaterally better than Mastodon; in my opinion, the main advantage of Bluesky over Mastodon here is the lack of instance-level blocks, which I think are grossly overused in the fediverse. OTOH, though, the ability to choose an instance means you do have a choice, however inconvenient it is. Bluesky having one appview, there is one choice. You get to see what they let you.

They built something impressive, and sure, it has its fans, but I worry it attracted people under somewhat dubious pretenses. It wasn't really decentralized in any meaningful way when users originally flooded in, and to this day the actual degree to which it is decentralized is quite questionable. I understand they have valid reason to fear giving up control in any truly meaningful way, but if they can't actually do that, then is there really a point to this? In practice, if Bluesky was completely centralized, it would basically make no difference. It wouldn't change much about moderation or how censorship-resistant Bluesky is, or any of that. It'd probably just make the damn thing a lot less operationally complex, and it would effectively be Twitter but for people who are left-leaning.

Thankfully for me, I don't really want any particular Twitter-like, but it's still hard to deny the importance of Twitter. A lot of the internet's personalities and creative talents are hanging out on these crappy social media platforms. I have my misgivings with the Fediverse, I've written at length about it in the past... But if I had to pick one, right now I'd pick the Fediverse over AT proto, scale be damned, subreddit moderator problems be damned, because it offers practically useful decentralization today and not "maybe some day."