Their homegrown protocol is meant to solve real problems with Mastodon, like that your home server owns your user name and can destroy or steal your account whe

Their homegrown protocol is meant to solve real problems with Mastodon, like that your home server owns your user name and can destroy or steal your account where you have all your followers. Account portability on Mastodon requires your current home server to be online and cooperate with you if you want to transfer your account to a different server. With Bluesky, you can do it as long as you have an archive of your data. The intention is to make choosing your home server into a minor implementation detail where the user is always in control instead of a hugely consequential upfront decision as it is with Mastodon.