I think PGP and asymmetric encryption is nice. (Also not too deep in cryptography)

My main problem with PGP is it requires a keypair from the receiving side. It is not a big deal, though how do you start a communication with a partner who has no keypair? It seems easier to send them a password on a different channel. Then to get them setup PGP on their side....

True that doing it via PGP would be more secure as in theory, only they have their private key.

What do I miss?

Also we might have different views on what "does not support" mean. Even a notepad supports encryption, I can just write the encrypted text in it. What I meant with not supporting is, I would have to use a separate extension to encrypt my gmail emails e.g. I could send them. Gmail could not read them, but I need extra steps to use it. This is what "does not support" mean to me.