Ehh, it's a double-edged sword. It's good that dumbfucks can't cause problems for genuinely good professors by review bombing them, but it also means that truly terrible teachers are horrifically common at a lot of institutions. Lots of university professors see teaching as an annoying chore they have to do so they can get back to their real jobs, and since teaching reviews have no real impact on anything, they have no incentive to change. In general, the more elite the institution is, the fewer good teachers you'll encounter there, which is a shame.