This is me bucking a trend. Cos it seems the only time Derpy isn't obsessing over muffins, she's delivering letters or adventuring with the good Doctor. I don't dislike people for doing it, I just feel there needs to be a bit more variety.
I know, but the point was that she herself hasn't expressed a rabid obsession over them. All we really know is that she (like most of the ponies at the cake shop) likes muffins