The MAC-10 etc was simply a “dump” weapon.
You walk up to confined space and “dump” the magazine into it.
It was never intended as a tactical weapon or at any real distance. It was designed to kill multiple occupants of a car or small room at close range. You drop it and run. Cheap and effective. It is not an extended service weapon, but more of a single use.
It looks kind of cool, though. Just like some old cars, someone ought to remanufacture a reliable version today with the same look.