The latest example is My idea about finding the largest prime number where OP asks about a distributed processing approach to find prime numbers. There was a comment: mersenne.org – pedja which OP accepted in another comment as showing the idea was not original. There are no answers, but OP seems happy. If nothing more happens this question will continue to be bumped by the robot. Should there be a closure reason to deal with this? I think so.
It's arguable that this question should be closed as "off topic", but barring that, I think the usual approach to such situations is to encourage the commenter to post an answer, which can then be accepted or at least upvoted (and that will stop the robot). If the commenter doesn't do so, then someone else can post the comment as an answer (by convention, using community-wiki).