My rule for internet observations is, any post containing "you" is argumentative and off topic. The topic is never the other commenter. Using "you" is often received as a personal affront, derailing the conversation. It betrays a me-vs-you superior attitude?
Not a bad rule, I have to admit (and true in my case, my post was certainly off topic). As a general rule it's a bit broad though, I think. If one wants to address another's points directly, it can be hard to avoid the second person pronoun.
It takes practice. Addressing the points as points instead of something 'you' said is about all there is to it. But we're so used to conversational modes, its easy to fall back.
