The notes on self-hosting[1], from somebody making $14k/month relying on Maddy, says it pretty realistically. The author goes into a fair amount of detail covering what he did and it sounds pretty simple compared to what it was ten years ago.

I'm not sure zealotry is the best way to push back against conventional wisdom, but otoh the parent comment didn't sound zealous to me.

In fact the more I read about Maddy[2] the more it seems to simplify running a mail server compared to when I did it back in the day. I mean you still have to worry about landing an IP address with a bad reputation but it takes care of soooo much of the rest of it.

[1] https://blog.healthchecks.io/2023/08/notes-on-self-hosted-tr...

[2] https://maddy.email/faq/