Are Doughnut Holes a Bug or a Feature?

One part of the tariff argument puzzled me. Justice Kavanaugh said that reading IEEPA to exclude tariff authority would create a "doughnut hole" in the statute given that many other authorities are delegated to the President. The gist of his question, I guess, is that doughnut holes are to be avoided.

But aren't doughnut holes necessary for doughnuts? It wouldn't be a doughnut without the hole. It would just be a lump of fried dough. So if a statute is a doughnut, why would having a hole be a problem?