This is fine if you're not concerned about metadata (date, recipients, subject).

pedantry: PGP hasn't been a product for many years. The product is "Semantec Encryption". GPG is still a thing.

Separately "just use <public key encription>" implies it's easy to do. Even if we ignore the fact that software support is generally terrible, there's the much bigger problem of convincing the people you email with to use it too. If you're not doing super secret or illegal stuff that's generally not a thing that's going to happen.