This would only work if, let's say, the video hosting market consisted of 10 competing companies having comparable shares. Different players would then take different sides, and the market forces would sort it out.

With the present-day monopolies/oligopolies it's different. If your financial well-being directly depends on Google listing your site, and Visa/MasterCard processing your payment, they can de-facto decide what is acceptable and what's not. And to force you to pretend that you share their views under a penalty of completely destroying your business.