Probably because it can be complex to set up and maintain
Such is mail and many other things, which falls on the admins. I see no harm in exploring what's what before deciding.
and more would be gained by educating users
Yes, users are the weakest link. Users are also the biggest challenge. Making them use 2FA on their phone? Easy. Retraining them to think more like me? Very difficult (assuming you get management buy-in).
Again, I'm trying to explore deploying an all "bells and whistles" mail stack that can cater to both an enthusiast environment (like myself) and one in a commercial/enterprise environment. Not having 2FA like I could get from cloud offerings may be a deal breaker for me.
I personally find your style of quoting a bit irritating, especially because you leave the whole original message intac
Gmail loves hiding the previous text with an ellipsis, making me not realize.
Why not quote in a manner we have successfully used for a couple of decades?
I've just recently started using mailing lists, so replying is still a bit awkward to me. (Probably be easier if we'd use forums.)