Compsci education is more focused on theory. Your prof is more likely to come from old-school corporate dev or 90s startups and probably has jaded views towards much of this new stuff like a lot of the passionate "designers and tinkerers" do nowadays

I'd bet this doctrine is probably being promulgated by the non-academics at trade schools and boot camps

In my class we learnt server and client side JS. I feel my prof's approach to webdev was quite modern. It was a very practical class and none of the theory we learnt was actually tested.

It is most likely a result of an echo chamber of students with no or little industry experience. It doesn't help that the younger people generally own client devices with more up-to-date specs.

Also, young people like to cling to new industry trends. It makes sense for them - if they would try to become an expert in something that is decades old, they would have to compete with people with decades of experience, while new tech creates a level playing field for the both the graduates and the veterans. This might also be one of the reasons for why we see such an diarrea of technologies in our industry - coding is mostly done by young people, many of them not more than a couple years into their careers. Pushing for new tech pays off for them.

Some, not all but some, new grads hear something from a prof or maybe departmental philosophy, and they will defend it to the death until they see real life for a while.