Youtube decides what content is permissible by being one of the large gatekeepers for distribution. They also are a large lever for large copyright holders to push on to hurt small content creators who have less recourse for action (DMCA and whatnot).
Youtube is ultimately private property. It is not a commons. That's my complaint. The whole Internet is a commons but there's no commonly shared infrastructure on the scale of youtube for content distribution and relating content to other content and to communities of people, unless you count search engines as that infrastructure.