Imagine a world without platform lock-in, where no ban or billionaire could take down your social network. That’s what ActivityPub has planned.
Mastodon has the seeds of this authority in that you can put links on your profile and then have them flagged by putting code on the website. So my Mastodon account could have a link to kazuyadarklightofficial.com and the flag proves I own/control that site. So if you know/can determine that site is THE KazuyaDarklight site, then you know you have the right Mastodon account.