You gave an example of an answer, after which people should know what to look up.

I pointed out legitimate reasons why a beginner would find that answer not helpful, and then proceeded to say that the answer is one I would give, but I would handle possible confusion by being ready with a list of useful references if the follow-up indicated confusion.

How did you get from that to the insane conclusion that I thought all posts should include the documentation for everything you used in answering the question?

People with unexpectedly poor backgrounds are like possible tangents in a conversation. They come up every so often, and you handle them with a lazy algorithm. If the person apparently has less background than your first response assumed, you deal with it by politely pointing out appropriate existing answers and tools.