I HATE CPM ads. It is free real estate for those cheapskates that don't want to pay anything. It takes about 3 impressions to get 1 penny.
Years ago, Google allowed me to "opt out" of CPM ads, which I did. Then, they changed the rules, and "re-opted me in". I strongly disapprove.
They felt they needed to force us to be slaves, for the sake of their ever-increasing profits.
I allow JUST ONE network - Adsense. I believe that the "ad pressure" argument is BullSpit. I don't want the riff-raff.
If you are not good enough for AdSense, why would I want your inferior ads, to degrade my website?
I am VERY aggressive with the ad balance feature. It STILL allows the sub-penny ads, which I think is also BS!
Remember the argument to allow webmasters to set a minimum $ click? THAT didn't go anywhere, and never will.
If they were able to serve sub-$0.00001 ads, I think they would. Only then, would webmasters scream.
If I could deny ALL CPM ads once again, I would be all over it. But the deck is stacked against the webmaster, in favor of the ad buyers - even the cheapskates ... ESPECIALLY the cheapskates.
Today, Google demands every hint of any revenue whatsoever, to the chagrin of many webmasters. Like me.
[edited by: Sally_Stitts at 7:44 pm (utc) on Jan 30, 2019]