[vec]

People are scared of hosting their own SMTP server because hosting an SMTP server is woefully insufficient for actually having mass mailings reliably delivered.

The hard part isn't actually sending the mail, the hard part is staying abreast of the already long and perpetually growing list of legitimacy signals you need to send to reassure understandably paranoid SMTP clients that they shouldn't mark your newsletter as spam. And you're not done even when the server is set up and configured properly; it doesn't take more than a handful of ignored complaints to start getting added to blacklists.

It's not difficult, per se, but it is a huge time investment for a service that centralized vendors can provide extremely cheaply because of economies of scale.

I'm all for moving toward decentralization too, but we're not going to get there from here if we don't understand and respect the incentives that lead people toward centralization in the first place.