Why downvoting so much?
I have seen this in a couple of courses already but this seems to be a real issue in the Polish course.
I have very often seen someone asking a question regarding grammar or simply wondering why his/her translation is wrong, without being rude or violating discussion rules. And there will almost always be someone who will downvote said question simply because he/she feels it's stupid. This only proves what I already firmly believe: There are no stupid questions just stupid answers. I honestly don't understand what's wrong about asking a genuine question in the discussions. Obviously said person doesn't understand some concept of the language and wants to improve and get some help. And actually that's exactly what duolingo - and learning languages in general - lives from: From people asking question, recognizing patterns and discussing them with fellow learners or native speakers. Besides that downvoting will also make the questions not display, so it's very likely someone will ask the very same question in the same discussion again.
I'm sorry I sound so frustrated but I honestly don't see a reason do downvote a comment unless the explanation it provides is factually wrong or the commenter is being rude. Otherwise it's just showing intolerance towards fellow learners who haven't progressed so far in the language tree yet, resulting in some form of misguided elitarianism.