Yes, but note that bulletin board/hacker news style sites can't handle the scale of submitted content that YouTube has to deal with. The purpose of all of these

Yes, but note that bulletin board/hacker news style sites can't handle the scale of submitted content that YouTube has to deal with. The purpose of all of these sites is to connect creators with consumers who will resonate with the content. Hacker News has a specific audience, which makes this much easier here. YouTube has the entire world/every interest/every audience!