The part I am highlighting makes it clear they can call a penalty on a hit to the shoulder if the receiver is deemed defenseless.
Will Hill is a freak, he's gonna be a stud for us and I expect massive things if he keeps his head on straight. Fast and knows how to cover and hit. Exceptional player. Now that he's learned our playbook, he'll have a full OTA and training camp under his belt and I expect to see the type of player we saw early in his Florida career. Has potential to be a top Safety in the LEAGUE.
The "unnecessary" part occurs when the defender uses his helmet or puts a blow to the receiver's head. A shoulder hit to the midsection is perfectly legal and very difficult to achieve in my opinion.
It is a hard call to make as well, and referees seem to be erring on the side of safety.