[massaman_yams]

Is it getting harder to self-host? Yes. Impossible? No. Most senders just find it easier to pay for it.

[pas]

Everything is getting harder as tech gets more and more complex. (As IT matures.) That's okay. The problem is that the incentives suck and there's too much business in email. The big ones have built their moats, and there's not much to do.

"SMTP" was simply never made to be resistant to this. (Nor the web in general.)