That was my answer for why I wanted to join, too! And I answered the “what will you contribute?” one pretty simply too, with the same things I try to bring to any conversation: my knowledge and empathy wherever they can be helpful.
I took the questions as the same kind of very basic filtering that my husband does for his tractor enthusiast Facebook group; he’s not looking for essays, he just wants to know people will actually read (and follow!) the rules and not be jerks.