Because I'd rather torque something to factory spec and lock it there with thread locker than overtorque something, possibly stripping the threads or snapping the head of the bolt off
. Torque values are set by the engineers for a reason, and I use them where provided. A properly torqued bolt with threadlocker is not going to back out. IMHO, play between the woodruff key and the pulley is what chips and eventually elongates the keyway, not a loose crank bolt.