Oh sure, blame the rise of ad blocking for the decrease in served ads. Remember when there were no adblockers except for tools like adzapper+squid? Yeah, those were terrible days with pop-ups, pop-unders, and punch the fucking monkey. Can't tell you how many times I was the Xth winner and won the prize of looking at an ad! And on a slow connection, the ADS would be the first thing to load, not content. So, publishers have only got themselves to blame for this terrible cat+mouse game.
Even today if I'm using a clean browser and doing general surfing, ads still make up 50% of a page's content. I'm reminded really quickly of why I use blockers.