Ads.
As long as there is even a marginal financial incentive to get human eyeballs on websites (as opposed to the viewers actually playing for services or, you know, just hosting websites for free because they are cool), this will keep getting worse.
A genuine desire to help incoming traffic doesn't really matter either. Anything helpful will be infinitely cloned, as long as there is incentive to clone it.
I dont really know a good solution either. Targeted ads are incredibly useful to small businesses, and that genie is out of the bottle.