I don't think it is necessarily gaming the system. I've done it a few times, and I don't give any craps about reputation, even a little. I get nothing by "beating" you in rep score, no gain by preventing you from earning rep. I don't really see what motive someone would have for behaving in the way you suspect they are. To what end do I block you? What do I gain from that?
Often, my decision to answer is with this mindset: the question is going to be closed for a technical problem, be it a near-duplicate, wording, "what did you try", etc. I can see it is a broken question, I can see close votes happening, and I vote to close too. At the same time, I am a human being, and there is another human being on the other end of this series of tubes who just wants to get something done. I empathize, and if I can take 60 seconds of my time to help them out, I do.
The question is possibly going to stay there for reference for some time, whether I answer or not, and it is going to be a honey pot for certain Google searches by yet another human being who just wants to get something done. If my brief answer can help them out, I feel it is time well spent.
When I'm on the hunt for answers, the last thing I feel like doing is clicking around the administrative banners of some Q&A site trying to find the person who had the good luck to ask their question in a way that garnered approval from the community. Sometimes the process works fine and the duplicate question, for example, is linked to a good dupe. Sometimes, the question is closed as a dupe and links to another question that is closed as a dupe, which in turn links to a question that was closed as a dupe and has a crappy answer.
In the end, I don't think it hurts anything, and I think it helps justify keeping closed questions around at all. If you believe it is a tactic to shut other users out of earning rep, I suppose you can take it that way; for my part, that's never my intent.