The primary purpose of S.O. is to produce a searchable corpus of answers with few duplicates and pretty high-quality answers.
The issue is that by discouraging participation in the community, you end up with a repository of old questions with decent answers (that may or may not be 'decent' anymore) and fewer newer questions with even worse answers.
My experience is that using SO is basically trying to find a middle ground between an answer that is too old to be relevant, but not so new that the effect of the stagnation of the community hasn't made the answer less than helpful.