I'm trying to wrap my head around that. How has Reddit ever been anything more than a link aggregator?
Social bookmarking site just means aggregator with a comments section.
Bookmarking to me implies a sort of persistence that one can go back to. Reddit is an ever changing stream with the page changing at each refresh.
That's like calling a raging river a Boat Parking Lot.
All the classic mistakes of forecasting (like Jim Cramer on TV):
0. Doesn't assign probabilities to the prediction.
1. Doesn't consider alternative scenarios.
2. Doesn't allow for the possibility that he could be wrong.