Sites are often dynamic, and it would take a hell of a lot of log grepping to stick a site to a specific player... particularly if said player uses one of the big providers.

IP addresses might be dynamic, but the provider won't be.

It only takes a couple minutes to grep for IPs and tell where someone is playing from, if they're coming in via proxies, and who previous characters were. That said, only Implementors have access to the log files.