I don't think every person who replies to you needs to answer the exact question you asked. This is a general conversation, and people can talk about any interesting point in any part of the preceding text. Tangent conversations are just fine here.
I don't think me writing a comment compels anyone to do anything about it, so, what's the problem? This is also the specific person I asked the question of originally to whom I am replying. I think when I ask a specific person a question and get a reply from that person, it's fair to expect that the reply answer the question. Wouldn't you agree?
You'd hope, but people gotta peep.
You also can't expect people to bother checking whether you are asking the question of the person you originally replied to. I actually thought about it myself for a second, and decided not to.