Hypocrisy has an added dimension, where the sinner exonerates himself while denouncing others, considers himself exempt from the standards he uses to judges others by.
Exonerates = excuses himself from the obligation, = the hypocrite excuses himself from the obligation he imposes on others. What you are saying is even less likely to be discovered by what someone writes on a forum. No? How can one call someone on the internet a hypocrite unless they see how they live? The hypocrite would have to actually write that the obligation he is imposing on others does not apply to him. No?
Right, it's impossible to determine hypocrisy on an internet forum if the person is anonymous. There's a looser sense, but it's more typically called "Pharisaism" and not hypocrisy in the strict sense where one might adopt an attitude of superiority along the lines of, "God, I think you that I am not like one of these."