It’s not impossible, many people I know and myself successfully self host their email. Yes it’s not trivial, and yes the ip reputation can be annoying to deal with (but it’s possible to cycle to another server to get another ip), but apart from that, if following the best practices (SPF, DKIM, DMARC, proper setup of the mailserver) once it’s set up it can run for years without issue.
To set things straight, I’m not saying that it is easy, but it’s also not impossible, and only giving up will further contribute to centralized email provider monoculture.
Not for everyone, but for those who can, I feel they should.