Why should `ToResemblance()` return a new instance every time?

I agree that with the current signature, because it's a method, I'd expect it to return a new instance every time. However, we could also consider making it a read-only property, and reuse the same instance. That would make sense because `Likeness<T>` itself is immutable, so no state would change between two calls/reads. This would be equivalent to Moq's `Mock.Object` property.

Are there compelling reasons to create a new instance every time?