They are hated because people on this board are damn lazy, and they need excuse for their laziness.
They just run a few hours (at most) a day, and do nothing else to improve themselves as runners. NOP members are 24/7 professionals who leave no stone unturned. Their take no prisoner attitude toward running makes people here insecure.
They are hated well beyond this board. Salazar is not a respected coach and other clubs hate on the NOP and distrust Salazar's closed door. One of the reason other camps hate Salazar is the size of his operating budget. Those I've talked to have said it is unlimited. Also, his own coaching progression. There is a reason why universities did not want Alberto Salazar coaching. He was coaching at Galen Rupp's high school. Salazar's brief running career and major health issues have always brought suspicion of his own use of PEDs. His first real coaching gig with Mary Decker showed PED use as she tested positive in 1996.
Trackbot! Dope Mary Decker
The reasons have always been well articulated and I've said before, Galen Rupp would not be hated the way he is if he ran for someone other than Salazar.