Literally not PGP, but clients built around it to make encrypted email easy. Read the article you linked.
EDIT: typo.
EDIT: typo.
I don't want to only talk to my tech friends. My best friend runs a small business doing nothing to do with tech and when I talk to him I want to be sure no one else can read/listen to what we're saying because it's private. There is no version where my friend learns to properly use PGP consistently so we can talk that way. The only reasonable way is WhatsApp or Signal.
It relies on a client having an HTML renderer, but the underlying issue is messages that can be tampered with.