They are hoarding knowledge and blocking preservation. At some point, the investors who dumped a quarter billion dollars into it will want a return on that investment. Last year, founder Adam D’Angelo indicated they expect to eventually IPO. But market conditions, combined with the results of their ad platform, may force them in different directions — a pivot, merger, or acquisition are always a possibility. When Quora shuts down, and it will eventually shut down one day, all of that collected knowledge will be lost unless they change their isolationist ethos.