Social media are just different. You can argue about who "owns" the content on YouTube, on blogs or Web sites in general. In a strict legal sense, you can come up with an answer.
In a broader sense, much "ownership" these days is shared. A particular site might "own" a certain piece of content. But creators can opt out and withhold their content. A company might own, in some sense, the content hosted on its site. That company might own the rights to monetize that content. But content creators also are provided "no incremental cost" rights to create their content. They also have the right to remove the whole site, at will.
So at some level, who "owns" it is not the question. To some real extent, all social media is a cooperative venture for everybody who wishes to contribute. No matter who "owns" a site, the value increasingly is created by the people who choose to contribute.