From my experience, this behavior is common when volunteers answer questions. Personally, I think this behavior that the author is seeing is because volunteer work is thankless and tiring (even with karma) and when you've seen a hundred questions and answered 20 of them the same way, it's easy to fall into the trap of feeling lazy or angry, and get aggressive either way.
This is the behavior I quickly learned to expect and brace myself against whenever I asked a question on IRC in the 2000's. I'd be mocked, the reasons behind my questions would be probed, and eventually I'd get an answer. I realized that If I asked an extremely specific question and, if someone probed, immediately provided full background, the mocking and probing would end, and I'd either get a shrug, or an answer.
This is not intended to excuse the behavior. I have just stopped being surprised when I see it.