The DNS system is centralized and prone to censorship.
You *can* add other DNS roots, but it doesn't really solve the problem.

I suppose systems like Namecoin or ENS might address the problem, if they get traction. Many on Nostr would have a problem with them because they are based on blockchains other than Bitcoin.
Personally I have no issue with that, although I don't know what secondary problems they would create.

The IP address space is also controlled and censored.