I end up writing in second person a lot. In fact, some of my comments in this very thread ended up in second person by the end. I really need to watch for this! I'm not the original blog author, but thanks for pointing this out - it's something I'm going to be watching for in my own writing from now on. (I'm kind of surprised I never noticed how bad it can sound.)
I think I fall into this trap when I want to generalize about my experience with others. For instance, if I observe some common behavior in virtually everyone I know, I might start saying "when you're such-and-such-ing...." because it seems easier than constantly reminding the reader that I'm simply generalizing based on my experience. However, I can see your point - that this really could be messing with the people who read it who maybe aren't directly my target audience. This might change my writing style significantly. :)