Well, it might be a lot of reasons which are best known to the users who are still inactive on the website that is making them not answer or reply to so many questions which are yet to be attended to. Some people might not have the correct answers to some of the questions asked, so they wouldn't be blamed for not having any answers on what they don't have any knowledge on.
Personally, I have come across so many questions on the website which I don't have any clue or knowledge on what answers to give, so I simply skip such questions and save myself the embarrassment of trying to answer on what I don't know.
On the other hand, it might be as a result of having less time to visit the website. We are in December which is a very busy month for everyone, so some people don't have the time to post now.