bdwalter, we do that we we can verify real people are contributing to the community to keep up the integrity of the data. Tweet me @jasonnazar if there is specific data I can find for you :)
The problem is you want to eliminate friction. If you can suck someone into your platform and then, later, say "oh btw please verify your email address to we can publish and share your salary. Anonymously, of course".
The way it works today I have to grid through all of these forms before I get ANY IDEA what kind of value you may or may not give to me.
You do it so you can get more emails. You do it because you use the slimy anchor-point tactic in your primary funnel.
Emails are important -- cool -- so just be honest with it. Make the field salary+email right away and don't bait-n-switch.