[jonnycomputer]

There is a privacy concern. And that might end up being a security concern depending on the threat model (e.g. social engineering attacks).

[EduardoRT]

So, you'd ask someone to SSH into a server, and you'll get some of his public keys (I think the default limit is 5 keys), what would you do with that? You can also just go to their GitHub profile and fetch the keys or ask them to send you their public keys, they're meant to be public after all.

Here's one of my public keys, for free: ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICIc3nOnSnsiAdkjAdH5WR9enQiPYWq1zAVsTDt60e91