Why do these questions get shut down after only a few answers?

It seems that the questions do not get answered thoroughly. Plus so what if it has been a year since the question was asked? Someone still might have a really good response that no one else has thought of yet the answer can not be given because - Why? Because time has elapsed? Because a certain number of answers were given? I think all the questions should be allowed to have on going opportunity for all to answer whenever they like!