Even to the extent that's true (and a lot of it is not), none of that explains why there are absolute zero email replacements, and indeed "security" people seem to promptly display brain damage whenever the idea is brought up. "Email-like" doesn't mean it has to be actual current standard email, there could be an "xmail" that has a UX near exactly like email but is more modern. But instant messengers (let alone centralized ones) are not a replacement for email and never will be, and the stubborn idiotic insistence they are is as surprising as it is infuriating. If you insist it's security or email, the answer is email, and that's how very important information will continue to be sent.
Although that said, and while not disagreeing about its flaws, I still can't let entirely go by:
>the protocol and the way it actually works in practice (hi, antispam!)
But anti-spam works fine with encrypted email (putting aside practicalities of no forging making spam harder anyway).
>asynchronous communication make it difficult to do encryption to the gold standard of quality
Nobody gives a shit. Asynchronous communication is well worth it.
>hope you didn't want to search your emails!
lol wut? If I go into Mail and searching something it can include encrypted emails the same as whatever else, why wouldn't it?