Maybe I'm suffering from selection bias...but while I have observed a large number of MTB riders, it's never seemed to me like the majority on this forum use MTBs.
I always thought that the majority used some derivative of road bike. Not a "racing" bike with a CF frame and 23mm tires, but rather a touring/cyclo-cross/or other "hardier" road bike in that vein.
In fact, it was the preponderance of cyclo-cross riders here that prompted me to choose a CX frame to build my commuter bike on, using various CX type components.
I'm not saying that MTBs don't have a place on a commute, and many do quite well on them, but I don't think that the majority use them for precisely the reasons you pointed out in starting this thread.
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Good night...and good luck