It appears to me, at least, that some questions remain unanswered after a period of time which suggests that a quality reply isn't going to happen. Indeed, perhaps the best responses are close to the date of posting and then the quality falls off and repetition occurs. Later posters do not read the earlier text and the quality of the entire thread suffers as a result with the good results hidden under dross or comments such as 'Interesting discussion' or 'Following'.
Would it be reasonable for threads to be taken off stream and archived say after a period of one year? By then all the quality responses that would have come have had a chance to evolve and long vacuous threads going nowhere are taken off the books.