@antekone is go so far as to say that Gmail isn’t Internet email, and I suspect that their system isn’t even SMTP standards compliant (though I haven’t had a chance to prove that yet).
It’s like any myriad of old proprietary email systems (AOL, Compuserve, etc.), and you’re right, it’s making its users more and more undeliverable.
A bunch of technomancers in the fediverse. Keep it fairly clean please. This arcology is for all who wash up upon it's digital shore.