I expect part of the problem is that it is so much easier to crack these thing than people think. Let's assume your name really was Web Head. So I run an address look up on your name. Now I have, if not your address, at least the address of several people with the same name. I can also easily find your phone number. Now I can check farcebook, twatter, and a few other places to find likes and dislikes, maybe even the name of your favorite pet. If you're a prolific poster I can probably find the names of you favorite movies. Favorite color? Pish! What are the odds it isn't part of ROYGBIV? I mean really, how many people will put in chartreuse as their favorite color? (I would but I can't remember how to spell it and need to look it up, which makes it unworkable for me.)
Yeah, not half as hard as people think. And with 150 million filing returns, it's a target rich environment. You don't have to have a 50% success rate, even 2% will yield a lot of data.