Using Referrer

Hi!
Does anybody know if there are websites that consider the referrer as important factor?
I've opened accounts with Postereous but whenever I'm trying to log-in and post by using ZP it tells me that the user and password are wrong, even though they aren't.
Are they deleting the accounts because I'm going straight to the login page and not using a referrer/clicking on a button to do that?

I hope you understand me, thanks!

I'm using private proxies and I validate the accounts about 1 min after I create them,
In the posting template I'm using private proxies as-well but not the same proxy as the one I opened the account with,
Yet the assumption that the accounts were deleted because I used different proxies while registering and posting(it didn't even log-in, so I didn't even post) can't be true since lots of people are using
their accounts from their home,school,work and such which the IPs are different in all these places...
:X

K,Thanks!