I absolutely agree with you. I really enjoyed your thoughts and analysis. For me, I do both. The question I ask is, am I responding to the person who wrote the post or am I talking to other people ABOUT the post. Imagine the difference between a Twitter Quote Tweet and a reply. One uses the other’s words for context of your thoughts and the other is writing thoughts back to the author. I use 2nd person or 3rd person based on the expected audience of my post, regardless of the fact that it is available for anyone to read.