I cannot recommend fastmail to anyone for the simple reason that if your account expires and gets deleted, anyone can create an account with the same email address and take over your identity. This seems like a massive security flaw.
Can you own a domain name? I was under the impression that it can still expire, which makes this solution about just as bad.
That said, I do agree that using a domain you own is better practice. However, I have been burned there before - I used a .eu domain for pretty much all of my email sign-ups for over a decade, then had the domain yanked away because of Brexit. Yes, my fault for not realising that this would happen (I lay some of the blame with my domain provider for not mentioning it to me at all).
The same thing is true of phone numbers, but it's more obvious that there's a finite number of... numbers... So they need to be reused eventually.