[Eiwatah4]

You do have some information in the browser you can't get to from the outside. For example, the filter with the most hits for me is "@@||192.168.$xmlhttprequest", which whitelists XMLHttpRequests to 192.168.*. A proxy can't really tell the source of a HTTP request. But that kind of thing is sometimes the only indicator telling the difference between an ad and useful content.