Crappy Design

And that is all neglecting the platform effect. People are on YouTube because the stuff they want to watch is there and the stuff is there because there is an audience. Because there is audience, people are willing to dump their marketing budget there. Because there is a revenue split of these marketing budgets, people are there publishing stuff. And so on and so on.

You can have the greatest platform from a technical point of view. If nobody is publishing good stuff, nobody will care.