Having a bunch of Tor site certs in your MacOS keychain has its own issues, so what is really needed is a way for Tor browsers to accept those certs directly without using the OS trust stores. The current practice of authenticating the remote site by PGP signature would remain more or less the same - you just wouldn’t have exit nodes sniffing traffic.
I’m also convinced that the whole reason Google has pushed TLS so hard isn’t some noble quest to protect people’s privacy and freedom of speech - it’s more to keep people from blocking their advertisements, which isn’t nearly so sexy an argument, but it has brought good benefits for a lot of people.