I like the idea and Nostr is pretty simple. My main queries are,

• They point out that there is no incentive to run an ActivityPub site and they seem to have paid relays instead. We can also make paid ActivityPub sites but, remember, there’s a reason the biggest platforms are funded by advertising and maybe these public spaces could be publicly funded? I don’t know.
• Managing cryptographic keys is hard and people already use Bitcoin badly. I guess the stakes aren’t necessarily as high, though loss of reputation might be bad. Are non-tech people actually going to do it? Do we need a ProtonMail of Nostr?
• Is there anything stopping ActivityPub applications from adding an optional cryptographic identity layer for author and account transfer verification for those who want it? I don’t see why not.

I just think that cryptographic signatures should be for those who care. Most people don’t. Most people have a silly pseudonym and react to memes.

I mean, banks still send me a PIN via SMS instead of verifying my identity using FIDO2. You’re telling me people are going to do the equivalent to make some shitposts?