That there is any discussion on "what" instance to join. I understand this is the whole point of being a decentralized system, but your average person doesn't care about that for social media. Maybe I'm wrong and mastodon.social is perceived in that way similarly to how bsky.app is for Bluesky.

I haven't followed mastodon in some time but the account migration thing was a pain as well, which I feel that the AT Protocol addresses much better.

Mastodon.social. These enormous monolithic servers offer the worst experience and degrade the whole network. And now joinmastodon.org points you at mastodon.social first, then a list of the largest servers.

In other words, centralizing.