A lot more people and organizations would self-host email if it wasn't a minefield. It's not laziness that Google and Microsoft have effectively decided nobody's allowed to do that.
I was part of a team ran EMail services for a ~15,000 person campus of a ~80,000 person university in the late 90s and early 00s. It was a full-time job for a team of people to keep things running, up to date, control spam, etc. It was a minefield 25 years ago! Literal years before GMail was a thing.
