:::You are correct in saying that the article will almost certainly be kept. (Whether I think it should be is neither here nor there). However, there obviously lots of people who want to redirect or merge it, and they are going to want to have there say. Speedy closures can be good thinks, but they only work where everyone says "yes that's obvious" and moves on. That wasn't going to happen here. The result of your closure was that the debate betweeen keepers and mergers continued as an  edit war and a discussion in other venues. So, to that degree, the attempt to move to a speedy result failed. Sometimes, even when the result is obvious, contentious issues need to be talked out so that when the conclusion comes both sides can accept it. As I say, I think your closure was good faith, and I agree was probebly the "inevitable result", yet it failed to close the discussion - and it is better that discussion continue on afd than take more disruptive forms.