I'd rather use Google's web storage than my own. I don't have the time nor the expertise to implement multi-region replication etc.
I understand that granting Google access to one's emails might be a dealbreaker for journalists, dissidents etc, though - so clearly Gmail is no good if you have legitimate need for PGP.
I would argue everyone does, most people just don't really think about what they are giving away. And how many emails a day are you receiving that a daily or hourly incremental offside backup wouldn't give you almost all of the benefits of "multi region replication"?
Turns out the quality of things like self hosted spam filtering is no match for the world’s most notorious data ingestion and analysis company
I have two or three emails a month get through my spam filtering. I don't consider fixing that to be worth the price of letting the world's most notorious advertising company have access to my emails