What an inane thread.
Starts off with an assumption that is not based in reality. Certainly not if you are referring to chareidi yeshivas.
Everyone knows that anyone who learnt in Brisk wears a sweater. They all do. And when I was recently visiting Eretz Yisroel, I lead in the Mir and saw many bochurim and yungeleit wearing sweaters.
I guess it is +1 for silly people who think this really happens. (Sarcasm).