For instance trace this IP 80.227.56.46 here.
Now if this was the IP of someone signing would you think it's legit? Especially if the person signing up was also using a hotmail etc. type e-mail address? Maybe the e-mail IP should match the signup IP, most ISPs include e-mail addresses, I know my IP and signup e-mail address could be checked to verify I am not trying to hide behind anonymous IPs and e-mail addresses.
the problem is, annon- proxy servers ARE legit servers themselves, when a person uses them, they are doing so without permission. they are just 'bouncing' through them.
The email account used to set up a FR account will have the ip number the person's ISP provides at the time, but that may not be the same ip# the next time the person logs on, unless the ISP is static, which most aren't. So you wouldn't be able to verify accounts that way without a lot of troubles.
What FR CAN do, is make sure that the email account providers, like yahoo, hotmail etc. are good ones which do not allow accounts to be made from proxy servers. This way you know you can trace and find out who the person is if need be.
I'm not sure, but there are limits to how many email accounts they all each pc to make, do they not? And I do know for sure that you must use your real ISP ip to create an account with them.
Another way for FR to tighten up accounts, is to demand that only your ISP's email be allowed, don't allow these 3rd party email services to be used to create accounts. That way, you KNOW who the user really is, and can simply call his ISP and have his account cancelled, or give it to the internet police for criminal charges.