Simply, people are talented or untalented, and ideas are academic or un-academic. Usually only the students are categorised by talent, but the categorisation of ideas extends beyond the university. But universities are here already, there was no choice. So a university starts with the assumption that some of the students are untalented, and that they must be prevented from getting a degree. The selection of students in universities is by repeated achievement.
Students take examinations, which only results in another examination.
Universities as institutions are increasingly aware of this, and increasingly integrated into employee selection. There are unfortunately still intellectuals in Europe, in the worst sense of the word. Universities pay them. The university serves as reserve employer for members of the elite, not directly involved in government. The third major function is research, and all of that research is based on the rigid distinction, between academic and un-academic.