They needn't hit their ad revenue much at all, because each user would just be in an experiment briefly, and they would aggregate results to get a general view.
They needn't hit their ad revenue much at all, because each user would just be in an experiment briefly, and they would aggregate results to get a general view.
Perhaps this isn't a great long-term strategy, but that doesn't really matter because nobody involved is incentivized to think beyond the short-term metrics that determine their bonus/promotions.
http://infolab.stanford.edu/pub/papers/google.pdf
Everyone—Everyone, who mattered (plus many others who didn't) knew exactly what would happen as Google went deeper and deeper into ads. But it made line go up real well, so....
To all external appearances, Google simply gave up on this cat-and-mouse game around '08 or '09. Big sites get ranked high (whatever changed seemed to give those a huge boost, around that time), everything past that's mostly webspam.
They prefer to spend money to keep the monopoly going such as the Safari deal.
https://www.sciencedirect.com/science/article/abs/pii/S03064...
The abstract from that article has a good introductory summary.