To me, the main obstacle is not the software (I can install a server in VM), it's the implication that I have to rent a VPS, or buy a DNS record, or subscribe to a different kind of ("business") Internet plan, when I already have packets flowing, just so that the email giants and everyone else believe I'm a legitimate participant in humanity. I feel stymied by email giants and ISPs that seem to collaborate to prevent me from doing something that even I agree is simple, to the point that I don't bother. That's 100% a social problem.
I think the desire to run one's own email server today mostly reflects a longing to re-discover the highly-accessible anarchy of the early Internet. Unfortunately, if that is ever to be found, it likely won't be in the form of complying with the highly-burdensome mostly-social requirements of our modern, well-centralized, email system. More likely, it will come from painting over it.