I set one up for our HOA as a unified conversation and notification platform. Everyone now has exactly one email address to remember to notify everyone of, say, a graduation party where there might be some extra cars. Nobody needs Facebook, or a Google account for Groups, etc. When people move, their addresses just get updated in the list.

The only trouble I had moderating it is people just love searching for whatever email was sent last to the list, necroing the thread and changing topics to whatever is on their mind. I had to set threads to auto-lock after a week or two of inactivity to force people to start new topics for things that are, well, new topics.

Fun fact: if you change the subject to a reply in Outlook (the desktop client; not sure about 365) it will automatically start a new thread. This feature was added because MS found that the "reply to last e-mail from intended recipients" was a common way for people to compose new e-mails.

Almost like the UX of mailing lists isn't actually that good...