I remember sky-is-falling-flavor-of-the-week newsletters from the 1970s; they probably go back further than that, but I don't remember firsthand. The difference is that YouTube lets millions of people find this without either having to subscribe to the newsletter, or the newsletter having to figure out who they are and send them a free copy.

In other words, what's different is that the gain is higher. The system was not always doomed, because the gain wasn't this high. Now that it is this high, the system may now be doomed.