Years ago I worked for a company that had ads appear on Breitbart. Retargeted display, not a direct buy on the site. People would screenshot the ads and light up our Twitter complaining we were directly supporting hate speech etc, so we asked our demand partner to stop buying there to avoid negative engagement on our social.
If your site gets a critical mass of negative attention brands can shut down your ability to be commercially viable, and effectively censor the content in a way.