I suspect you are using terms that to you are obvious, but to me are technical terms that don't mean what they seem to mean based on the words involved.

Based on what you've said here I don't know what you mean by "self-hosting". I have a package that I purchase from a company that provides me with my email and web hosting. I pay them, I configure my web client to connect using the details they provided, they deal with the configuration.

They are qualified in this field, they have certifications.

Everyone here seems to be using terms that obviously mean something to them than is different to what the terms imply to me. I have machines that connect to my email, hosted by the ISP with whom I have the contract. To me, that doesn't mean "self-hosted" ... I don't do any configuration of DKIM/SPF/DMARC/etc. That's all done by the people I pay.

So ... I really don't know what you're talking about. I suspect you know too much to be able to communicate effectively with me, who knows nothing. It's plausible that the field of discourse is simply too technical.