It was less of a problem a few years ago, before groups started claiming that Google & advertisers were explicitly supporting / promoting controversial content.

It was less of a problem a few years ago, before groups started claiming that Google & advertisers were explicitly supporting / promoting controversial content. With the PR fear in full swing, there is very little upside to either party allowing advertising. For example, groups were actively hitting the top commercial websites and then visiting Breitbart so they could screenshot retargeting ads to use in shaming the company on social media.