"What?" Actually it can. Websites make their money from web advertisements, and in most cases is their only form of income. So if most of the people that visit the website have an ad blocker on, they lose money that they could've earned, and might have to downsize their website significantly. Some websites have been forced to shut down because they weren't making enough money to operate on. So the next time you see a pop-up or "CLICK HERE TO WIN AN IPAD!", think about how you are helping the company out.