At least if the question was already staying around unanswered for some time, I feel a comment-hint can be useful, if used correctly. Think of the following:
I have not used it myself, but would XYZ (link) fit your needs? Please give it a look and report back. If it does, feel encouraged to answer your own question with it, including a short description and arguments.
This would be a double win IMHO: The questioner does not feel "ignored" (so it's good for the reputation of our site), and if (s)he comes back and does as asked, the real answer will be available to future visitors. If (s)he comes back and just leaves a comment, the "original commenter" can – depending on the outcome – post the answer, or delete the comment.
We should only recommend software we actually used ourselfs: I wouldn't make that a law. Sure, that's the best and recommended way. But if I know a software exists, fitting the OP's description, and has good reputation (e.g. I know people using it, have read "objective" reviews, or got the clear impression in other ways), I would make that an answer.