An ad network cannot tell the difference between a real click and a fake click based on the HTTP request itself. They have to rely on probability models to guess whether clicks are real or fake. The mere existence of an extension like this should prompt them to reconsider their options.
If you think about the ad model for print and broadcast media, they don't bother trying to track eyeballs. They know it's impossible. You pay for your ad to appear a certain number of times, and hope people pay attention to it. You can't know whether a specific newspaper gets read by a dozen people in a hotel lobby or lands on a driveway in the morning, to be trashed, unread, at night. If an ad runs on television, the advertiser doesn't know if it's being watched by the whole family, or just the dog.
That's why ratings services, like Nielsen, exist. People get paid to have their habits monitored, and those samples are extrapolated.
Ad networks can, if they so choose, blacklist sites based on a perception of "fake" clicks. Those sites are not necessarily responsible for fake clicks, and they certainly can't do anything to stop them. You would not, therefore be harming the site operators. You would be harming the ad networks that pretend that they know more about their own service than is possible.
Destroying the viability of pay-per-click is (arguably) something that would be an improvement in the world of HTTP publishing.