Comment by xp84
Even following all the directions is not trivial, nor is it easy to troubleshoot when something mysteriously goes wrong with what is usually a pretty vital connecting piece for most of your digital life.
Plus all the good places to host your personal domain cost money, so now people who have gotten email for 'free' for 20+ years now have to start paying a monthly email hosting bill and annual domain registration fee because some 'nerd' told them they "should"? And if they ever forget to pay either one, suddenly their email is down and their email 'identity' is at risk of being resold.
This advice is exactly like changing your own oil: Anyone with enough interest in cars and dedication to learn the steps certainly can easily do it, yet nobody should try to convince their grandparents who aren't already highly self-motivated to start doing it.
Eventually you have to trust someone anyway.
If you don't trust Gmail, then you have to use Proton to host it, don't trust them then your on AWS, don't trust them you still need you ISP to play nice with a home server.
Unless you want to raise your own carrier pigeons...