thats a pretty common mod, duner/hillclimber bikes, a lot of them have those chopped out, there is plenty of strength in the frame with or without them, you wont fold it up if thats what your worried about
who in thier right mind is going to trade uncut full bores for those wierdass racecuts, wtf are dangly dingleberry bits supposed to be, if someone already had uncuts they could just ruin thier own lmao