Yes, the problem is that quite often people ask questions that either have no readily available answer (either they're way too specific, or incredibly vague), or are much better suited to the weekly (?) short answers to straightforward questions phase.
For example, a lot of the early medieval questions are either things like "I'm writing a Vikings fanfic; what colour horse would a member of Ragnar Lođbrook's crew have ridden in July 812?" or "What did people think of Rome from 1066 to 1450?" Both of those can be answered, but any satisfactory answer, especially for something as vague as the second one, takes a lot of time.