I wouldn't say Houses can afford to specialize so much as they don't have a lot of choice in the matter. Where it's relatively easy for countries to diversify while retaining excellence (they have a lot of people, after all), Aristocratic Houses with under a hundred people to their names are...
Right, seeing as commentary is welcome and I have some experience here (I study politics in University), I have a some relevant thoughts. I'll go in order, as much as I can.
Where food is concerned, I'd like to emphasize this point: It spoils. Rather fortunately, only societies with the lowest...