Advertisers didn't care for over a decade until partisan agitators such as Media Matters and Vox methodically cherry picked screenshots of brands next to maligned youtube channels, and then contacted brands threatening to publish names and shame if they didn't pull their advertising.

The result of this short-sighted crusade was Youtube becoming unprofitable for millions of small creators around the world, and people of all sides of politics suffering including non-political LGBT creators.

Any particular advertiser needs Youtube more than Youtube needs the advertiser. Youtube has a critical hold on the young adult market in particular. If Youtube just said, "if you don't like it, Pepsi, someone else can enjoy this ad space instead", what recourse would they have? In conclusion Youtube demonetizes because they want to and need an excuse.

It's also a great way to whitewash history. Want to educate the next generation about Hitlers atrocities? No money for you.

Basically anything war seems to be getting demonetized these days. Advertisers only want to appear next to cats on roombas.