[jeroenhd]

How do I convince the tens of thousands of other servers that my private key can be trusted without some kind of third party trust architecture?

There's DANE but outside of maybe two countries that's impractical to set up because DNS providers keep messing up DNSSEC.

[the456gamer]

If you are trusting a user since they are the same one that originally contacted you, you don't. It's tofu

[lmz]

I can't believe this was downvoted. Seriously a Certificate is binding a public key and the attributes (mainly the identity). If you don't need to use the attributes, you don't need a certificate!