Just to see, I threw in a burner email. Not only do you give your email, but you're forced to make an entire account with demographic data[1]. If you navigate back, you're presented with that modal again. You never get to see the data without entering everything. If you try, you get an error in the modal with the zip code highlighted [2].
No big deal - just throw in a fake zip, right? Nope! Everything must be completed[3].
Yup. I typically do these things with entirely fictitious numbers before (sorry Marketing Community Managers if I screwed up your results) to see the entire workflow and stopped at the email/linkedin thing. For me at least LinkedIn already has a really bad reputation for exploiting the crap out of your information so I immediately cringe when people try to link to it or use it (same with the Evernote business card scanning service).
Shapov, there is logic and algorithms that prevent bad data from entering the data set. The data you entered for example would not go into the data set.
No big deal - just throw in a fake zip, right? Nope! Everything must be completed[3].
[1]: http://i63.tinypic.com/2rm0g95.png
[2]: http://i68.tinypic.com/ezhbvq.png
[3]: http://i67.tinypic.com/ncm3wn.png