I don't see how a definition is unsatisfactory just because it doesn't account for nuance and complexity. A definition is, by its very nature, reductive. It helps us understand something at a basic level by reducing it to its simplest terms.

If you asked me what a restaurant was, there's no possible way I could give you an answer that accounted for all of the different types of cuisine, styles, etc. And we could get into debates about whether or not taco trucks, or bars are restaurants, and what about restaurants inside grocery stores, coffee shops that sell hot food, and on and on...

It doesn't follow that a restaurant is something we can't define, or easily recognize, or that the true definition of a restaurant is not a matter of truth but of understanding.

What you are committing here is the fallacy of the beard. That is, when something has a fuzzy boundary associated with its definition, an over reaction is to claim that the thing in question cannot or should not be nailed down. Does a beard exist with just one hair on your face? Ok, maybe two, or three, or 100?

We don't know. Therefore, is it a mistake to say that we can know what a beard is? And recognize it when we see it?

The question answers itself. But the point is, definitions matter, not as end points in a discussion, but as starting points. The nuance, and complexity can be considered afterwards.