And herein is the problem. None of the sites mentioned run off of a single server, they run in server farms typically called CDNs (Content Data Networks). So you can whitelist slashdot but without also whitelisting each of its CDNs slashload won't load. To make matters even worse most CDNs are dynamic meaning your traffic may hit CDN01 to start with and the next request it hits CDN02 and so on. Oh by the way, the same CDNs hosting slashdot could also be hosting the trackers from what ever site so if you do decide to whitelist a particular CDN you've also white listed the tracker. This is just scratching the surface of how complicated the underlying infrastructure is.