I think this policy is mainly directed at those affiliates using “arbitrage” and not so much at those who actually have a functioning web site.
Too many people were jumping on the Google Cash bandwagon. These were the affiliates who were too lazy to actually create a website and simply ran an ad in Google and sent the traffic directly to the affiliate program.
Google wound up with pages and pages of ads all going to the exact same website selling the exact same e-book, or whatever.
It was making their directory look even more worthless than it actually is. :1circling