This is a pretty meaningless sentiment. There are plenty of things one can study that will lead to more ignorance and less well-roundedness. In the extreme, this is pretty much how cults can operate. I believe it also applies to a number of subjects in mainstream universities, but I am not going to hop into that fire pit.
It's a university.. there are a broad array of departments and courses, and I am saying that a handful of them at a multitude of universities have the potential to close minds and lead to more ignorance - this broad statement isn't too controversial - witnessed by the very vocal debate about it. I am not going to jump into the pit of the specifics of that debate though.