Acoustic instruments in their own monitors? Generally stupid. I've heard of drummers needing themselves in the monitors. Gotta ask yourself why? I like the thought of sending the drums back to the drum monitor with some delay to discourage that stupidity.
Week to week, for 20 years, dual mixes of FOH & foldback stage monitors of live horns, sax, trumpet, t-bone, flute, along with percussion, congas, bongos, timbale, and yes those `stupid' drummers. Last I checked, those count as acoustic instruments.
Why? Because that is what the job requires. Period. And to much satisfaction for the musos. It would seem we come from different experiences.
I generally have great respect and admiration for the musos, artists, and performers I have worked with and for over the years. Some I can & have referred to as touched, characters, divas and a PITA at times, but to call them stupid for wanting to hear themselves in a foldback because they play an `acoustic', never.
Boy, did this go off the rails to the OP topic.