I used to work for a "big adnetwork" and this is how it worked there.. AdSense is probably similar.
We tracked conversions, where possible, on our advertisers end and used that data to calculate conversions per click for our publishers. We'd use this metric, mixed with a few others (ctr, # of impressions, # of fraudulent clicks, etc, but mainly weighted towards cvr) to generate a quality score for the publisher. The quality score was between 0 and 1, 1 being "awesome" and 0 being "awful".
We'd use this quality score to discount the price per click publisher was paid. AdSense is likely doing something similar because their CPC/CPM rate/split is undisclosed and very private- likely because publishers will get paid drastically different amounts per click depending on their traffic history.
Anyways, when a publisher falls bellow a certain quality threshold, we'd drop their account because they are, in the end, not making the advertiser any money and likely hurting our future relationship with the people that pay the bills.
Social traffic usually falls into this poor quality area into this area because it doesn't convert well, has a low click through rate, and includes lots of accidental clicks.
Why not just pay the publisher the (possibly low) value of their traffic, while also providing the publisher with the tools they need to improve their traffic quality? If the site never improves then it simply never makes any money.
The networks see low quality publishers as diluting the overall quality of their network. Since advertisers only care about traffic that converts, low-quality traffic hurts stats because it makes CTRs and CVRs drop even if the overall CPC/CPA is the same.
There are absolutely ways to educate publishers and advertisers, but the easiest solution for the network is to just nip it at the bud and drop low-quality traffic.
We tracked conversions, where possible, on our advertisers end and used that data to calculate conversions per click for our publishers. We'd use this metric, mixed with a few others (ctr, # of impressions, # of fraudulent clicks, etc, but mainly weighted towards cvr) to generate a quality score for the publisher. The quality score was between 0 and 1, 1 being "awesome" and 0 being "awful".
We'd use this quality score to discount the price per click publisher was paid. AdSense is likely doing something similar because their CPC/CPM rate/split is undisclosed and very private- likely because publishers will get paid drastically different amounts per click depending on their traffic history.
Anyways, when a publisher falls bellow a certain quality threshold, we'd drop their account because they are, in the end, not making the advertiser any money and likely hurting our future relationship with the people that pay the bills.
Social traffic usually falls into this poor quality area into this area because it doesn't convert well, has a low click through rate, and includes lots of accidental clicks.