It's reach and UX.
Normies can use it.
People who were in early days of Internet remember who bad email mailing lists were for organising anything. Mailing list, Usenet, IRC, are all now dead because no one could invest to UX in these early open protocols.
In theory you can reach all users using a mailing list but oh boy, good luck with that one, unless all of your peers are kernel developers.
> People who were in early days of Internet remember who bad email mailing lists were for organising anything.
Most of us miss the simplicity of mailing lists.
I lived in a new (at the time) neighbourhood back in 2008, and we had a neighbourhood mailing list which was very convenient. Nobody had issues with using it, because there’s very little to learn if you know how ti read and reply emails. Sure, we had to explain “reply to one” vs “reply to all” to a few people, but that’s entirely it.
Mailing lists fell out of fashion because of marketing and trends, not because of any inherent limitations.