I've had a stem bolt fracture while just loosening it, using very little torque, on a bike I had been riding! ...The bars had started creaking, so I was going to grease the threads and re-torque the bolt.
The broken stub piece came out easily as well, using an easy-out and almost zero torque.

And that one was 1980's Bianchi, full TTT bars and stem. Used parts though, so unknown history. Picture below.

So I agree, it's very bad practice to put any unnecessary bending stress on a pinch bolt, likely why so many seat post pinch bolts break, after the ears go past parallel.