The target audience for these sites are obviously people who want more traffic and want to make money with their sites. Bigger sites couldn't be targeted cost-

The target audience for these sites are obviously people who want more traffic and want to make money with their sites. Bigger sites couldn't be targeted cost-effectively because they would have to make a lot more noise for themselves to even show up in the analytics reports. Also, the people reading the reports are more likely professional and aware of those techniques. Their algorithm is probably not so advanced, so they just shoot lots of requests to any site they can find. Luckily for them, most sites are small and unsuccessful.