It would be unrealistic to expect all questions to be answered.
While we have a strong core of people, there are always questions that will be passed on from a variety of reasons. The two biggest reasons I pass on a question, is lack of information that is asked for upfront, and it may be a question that I can not provide valuable help with. While I spend a considerable amount of my free time here, I just can't do it all the time. I volunteer for this to try to help people, provide some understanding of the industry and learn.
Sadly there are some posts that go un-answered. That's life. Especially when you take the free route.
It is better to get no response than a response that takes one in the wrong direction. That would be a tradgedy to do if our goal was to just "answer every post"
I can spend hours trying to help just one post. Sometimes I spend an hour researching a problem, that I only learn I am not able to adequetly help, and therefore do not post a reply.
And then, some questions just plain do not deserve a response. For example, When someone posts that they can't find the oil pan on a car and want to know where it is, you have to ask yourself what are they going to do with this information. Is it reasonable to respond? Are we going to actually help someone. This is easily learned through a google search should they really need to know.
Furthermore, i don't go into questions that are more than a couple days old. Most auto repair problems are not a casual situation, it is more often needed information almost as soon as the question is posed. I am better off helping a fresh question than responding to somthing that may already be solved or given up on.