1) Despite an appearance of being "left leaning" (according to polls of faculty political sentiment) they continue to gatekeep education behind prohibitively expensive tuition that is out of reach of lower economic strata without crippling debt, and have simultaneously struggled to produce graduates whose economic differential easily makes up for that expense and lost work time.
2) They enjoy a tax free status while receiving significant tax money despite many failing to grow their student bodies in tandem with the growth of the US population, leading to people questioning whether they deserve those benefits as institutions that serve the public.
3) There is a sentiment that basic literacy and numeracy of graduates has dropped over the last decades outside of a narrow area of studies, because of a shift to a model where students are customers buying a credential instead of getting an education.
(These are all interrelated, of course.)
In reality I don’t think people’s political opinions change very much and they are just mad that their children individuated.
I think this probably the case as well. If I look back at how my own views shifted, the shift very likely would’ve happened regardless of if I’d attended university, assuming everything else was the same. It wasn’t the university that resulted in the shift as much as it was my getting out of my local bubble out into the world and experiencing it for myself.
Basically any kind of life experience that brings a young person to actually think and more deeply consider the world around them is likely to result in some level of individuation and shift away from inherited views. It’s perfectly natural and healthy.
I don't think you're wrong about the axes for "academic intelligence" or "political outlook". But those are just two of many. Geographic, racial, economic, class (in the European sense), language, culture .. these are all equally valid, and likely to vary more in a university than in a workplace (even in the military).