There's a zero percent chance that a company like Youtube would allow its content to go completely unmoderated. It has to moderate its content. It has advertisers who are associated with content and it has to keep on the right side of copyright law. Also, no website operator wants the hassle of dealing with court orders because posters are engaging in verbal slapfights online. Your proposal of A would have an EXTREME chilling effect on speech.

Because Youtube exists in the real world, and because earning money through ads is a hell of a lot better for business than trying to get people to pay for content, C is always the best option for them and for every other content provider AND virtually all small and independent content producers.

Otherwise, companies like Youtube would be forced to gate entrance to supplying content by charging hosting fees for content. You are seeing the tree and missing the rest of the forest.