Yeah, a haystack full of needles is better than a single needle in a haystack. That is to say: having the same information repeated tons of times is better than not being able to find the one canonical place the information is written.
Are those the only two options? How about a haystack full of maybe-needles, where each answer is subtly wrong because no one has the willingness to go through and vet all of them?
Simplest thing would be to delist closed questions from search (including Google).