Ask HN: PGP Keyservers in Blockchain

I was wondering: do you know any keyserver using a blockchain technology? I found "classic" PGP Keyservers (like MIT) but I'm not really fond of any central entity (either Google, Facebook, MIT... or any other) managing my identity and it seemed to me that the blockchain could be a good technological candidate for that use-case (using BigChainDB for example: www.bigchaindb.com).

The blockchain could store mappings between email and public key. The addition to the blockchain should be guarded by a kind of challenge (like answering to an email crypted with the public key).

As a companion, an IMAP/SMTP server (or mail application plugin) would be able to sign/crypt/decrypt/check signature "transparently" (like any spamassassin for example, so it could be user-friendly) by checking either local db or asking to the keyserver...

Or the keyserver could implement the OpenPGP Server Protocol...

I'm surprised that I couldn't find any information on that kind of idea (mixing Blockchain and Identity Management) so maybe there's some strong drawback that I didn't see... Or maybe I searched with the wrong keywords...?

Any help would be appreciated Thanks in advance