To me the categories on DC are just guidelines, helping us to find the general type of food we are interested in at the moment.
And the boundaries seem fairly flexible.
If I had a question about, or a recipe for, chop suey, something that as a child was allways served in Chinese restaurants but which apparently was never, ever a dish in China, I would probably post it under 'ethnic'.
As I understand it, the dish that was created in America by Chinese immigrants working in restaurants and is about as Asian as chili or franks and beans.
(As an aside am glad the stuff has gone the way of the dodo bird or the great auk.)
Realize that what seems ethnic or exotic to one person may be another's everyday fare.
The categories seem to work and if the administrators want to come up with another system, fine by me.
Meantime, I am just interested in food and not lexicography.