Well, my 2 cents is as follows. It all comes down to winning. Once upon a time, football was about winning at any and all costs. Before the league put flags in the QB's pockets, defensive players would be gunning for the QB.... knock the QB out and your chances of winning were greatly increased. That's football, like it or lump it. Football is a contact sport...., a defensive player inducing contact is pretty much trying to shut down the person receiving the hit..., that's their job/objective. If you send 300 lbs at full speed at any person.... that's pretty much intentionally trying to hurt someone.
If I was a professional defensive coordinator, I would send 8+ at Brady early and often... I'd tell the defense to do their job and "make contact". And would also remind them, if they don't succeed, Brady and BB are going to absolutely humiliate you...., all day, because they will NOT let up.
In closing, any one who says trying to knock some one out in Football, Boxing, Rugby, Aussie Rules, Gaelic Football, Hockey, or any other "contact" sport as being unprofessional is being unrealistic and should start following some other "non" contact sport such as synchronized swimming, figure skating, gymnastics, etc.