No one wants to get on their professors' bad side. The brighter students quickly know what they're expected to do to get good grades and if they have opinions that are not welcome in the classroom or on campus, they keep it to themselves.
Here's an interesting passage which illustrates the problem of only recognizing repetition:
The absence of a rational foundation or discourse about the truth to ground moral certitude has consequences on the form of the message as well as on the tone used to convey it. Today's moral message is not explanatory, as it was for example in the case of Las Casas in the sixteenth century, who defended the dignity of the American Indians, or of Thomas More, who was indignant about human misery. Our message, on the contrary is loud and repetitive. It is proclaimed vehemently and always carries a threat against its adversaries. It creeps in through all the cracks of social life because to be convincing it must be constantly repeated. It compensates for its lack of justification by its ubigquity and omnipotence. Its "human rights"-ism is incantatory to the point of inducing nausea. It disguises the lack of a crucial backdrop by hogging the stage, leaving space for no rival. What it is unable to obtain through persuasion or debate, it obtains through the stifling of adverse ways of thought, which are vilified as soon as they dare to show their faces. Evil is not rejected by reason, but hated out of indignation and denounced through invective. At the same time, discourse about the good is set to the tones of panegyric and the smell of incense. p. 77 Chantal Delsol, Icarus Fallen.