Perhaps you could name some of the well known pieces in the western canon since the advent of 12TET that are written for non-12TET tuning/scale systems. Certainly there are folk traditions that veer closer to non-12TET but there's very little music for voice and instrument in western culture that isn't 12TET because so many of the instruments are tuned to 12TET.

Barbershop quartet is the style that comes to mind where it's used all the time

I did not know that - thanks very much for the enlightenment!

My wife and 1 daughter both sing in acapella groups, but their various different groups over the years have never done anything in JI, although my wife also sings Balkan songs which are whole other story of course.