Okay, but the end result of your decentralization is exactly what Mastodon is. Which is in order to be truly decentralized instances should have the option to o

Okay, but the end result of your decentralization is exactly what Mastodon is. Which is in order to be truly decentralized instances should have the option to opt into one or more shared administrations. But functionally that ends up being the same thing as what you complain about which is that ultimately administration and/or accounts are localized at certain administration levels. 'Instances' in Mastodon are that administration you want. If you try and force a shared administration and say 'This is the central administration that you register on and instances share' then you no longer have a decentralized social network. You have Reddit.