I remember that my newsreader back in the early 1990s did exactly this. I had trouble posting the first few times because I took the message to heart and didn't want to waste other people's time. But I quickly realized that other people didn't follow the same suggestion, which meant that I should ignore the message, and even interpret it as wrong.
Why is it wrong? For example, consider the second message. Suppose you haven't read all the messages in a thread because you've been on holiday for the previous few days. But a friend pointed you to a message in the thread which specifically mentions your name, asks "could you verify this for me?", and doesn't have any followups?
Why should your newsreader force you to read all of the thread in order to answer something which isn't in the rest of the thread? Yet the only option there is "cancel".
Furthermore, "at least 10 seconds" is completely wrong. People killthread, plonk people, and develop other ways to ignore discussions. Assuming 4 hours per day means people can handle at most 1440 messages. There are 276 comments already in this thread, but I expect most people sampled a few messages on each major branch, skimmed a bit, and perhaps did a text search to see if someone mentioned a key word. Most assuredly, the entire HN readership did not read this entire thread.