I didn't mean to replace YouTube as a product specifically. I meant that this happened over 30 years ago between the networks and cable. Network TV dominated and cable had the same problem with attracting both views and content producers. The point of the matter was to not complain that it is impossible; it is just hard. However, others have already solved a similar issue so the lessons learned can be applied here too.

Now this actually raises an interesting question. Would you define a monopoly based on the service a platform offers, or the resulting combined services created by everyone utilizing the platform? One could argue that any service that allows you to upload and share video is a replacement for Youtube from the perspective of the platform's service. But you're auguring that unless another platform has a comparable amount of content, it is not a viable replacement.