This is the reason behind essentially every reply I've ever seen to this question.

"I like it this way because it's always been this way and once you change your entire email workflow and customize your email client, it's almost as good as PHPbb"

Forums are built for threads and are immediately visible and accessible for everyone, not just people who want to spend their limited time dicking with email clients.

Mailing lists are the proto-discord: knowledge locked away from the public behind a special frontend and elitist attitudes. It's only better because the list is technically visible, but only in the worst, most low-effort way possible. You dump a raw txt copy of the entire thread unstructured onto the user and make it their problem to figure out. After all, your email client makes it easy to read, so why should you care about what anyone else needs?

maybe the old tools are prevailing for a good reason.

I prefer people to email me because half of the time they figure out their problems while writing them.

it's not an absolute rule but people who don't do their homework gravitate towards calls and messaging because they just don't prepare their questions.

asynchronous communication puts the burden on the sender, where it belongs.