I genuinely don't understand the appeal of using ProtonMail if you're already using PGP. That's all ProtonMail is, convenient PGP. If they are already using PGP

I genuinely don't understand the appeal of using ProtonMail if you're already using PGP. That's all ProtonMail is, convenient PGP. If they are already using PGP they can just use Fastmail and have the same privacy benefits.