Certificates just add more keys to worry about. The beauty of SSH is that it does not add hugely trusted parties in the name of convenience, while the UX of TOFU (trust on first use) is pretty decent.

The real solution to break out of these UX/security tradeoffs is to put domain names on a blockchain: then you can simply rotate the key in your DNS record, while the blockchain model is such that you need to compromise many parties, instead of "one out of many parties", as with CAs.

Tracking Bitcoin chain for DNS updates is lightweight enough that it can be built into OS alongside other modern components such as secure enclave, TCP/IP stack and WiFi/BT/5G radios.