I do not have to time to hang about in forums, nor to idle on Discord or IRC.

E-mail, on the other hand, is a constant. I can snooze it, read it on Emacs, file it with custom rules, deal with it however I want. It doesn't require any particular app, any particular form of formatting, it doesn't give me points, badges, weekly recap emails, or require me to upload an avatar.

I feel mailing lists are underrated, and reading from this thread, it's mostly because the software to run them is as intuitive as Sendmail.

Discourse has terrible UX compared to other online forums and even mailing lists.

Your claim that it's superior needs to clarify exactly what is superior about it.

Is Discourse easily searchable from the outside? I was looking up transaction behavior in Postgrsql last night. I came across such an old school mailing list. The utility was that it appeared rather high in the search results.

Reminder: 'modern' and 'old-fashioned' are political epithets, not measurable quantites.