tl;drAllow me, as the communicator, to try to expand my metaphor in the manner I wish it to be understood.
Say the cake is me. My personality is what my cake "looks" like. My behavior is what my cake "tastes" like.
Let's imagine that the functions are the core ingredients of my cake, the cake of me. So I have a mixture of them all, in varying quantities, as does everyone else. To be complete, let's say we all possess all 8 tasty "ingredients": Fe, Fi, Te, Ti, Se, Si and Ne, Ni.) They get measured in finite quantities creating a huge array of possible combinations. But that's all there is in the basic recipe. These 8 "ingredients". My appearance and flavor can thus be anticipated to a point, based on the commonalities shared from the "basic recipe".
If that's all that was in my cake, perhaps you could be so bold as to imagine you could predict what my cake really "tastes" like. But that's not all that constitutes the cake of "me" at any point in time.
There are other ingredients that are added to the "basic recipe" and thus get mixed into and then baked into my cake, ingredients that you may have no awareness of. My life experience, the kind of parenting I received, my values, relationships, the cultures I participate in, my physiological constitution, my gender, intelligence, other genetic variables etc etc ... arguably these are all factors that mix into the basic recipe to create my "cake." The homogeneous batter that comprises the sum of all of my raw ingredients differs now from the basic recipe, but still we know much of what is "in" the cake, so could still even imagine what it might "taste" like.
But what's important here, what I want to emphasize, is the baking. The process of baking creates new chemical structures, changing the essential nature of the cake. The infinite number of extra ingredients mixed to the batter interact with the basic ones in unpredictable ways, create something new each and every time. Even the time of day, altitude, humidity levels affect the baking, external factors completely unrelated to me, to my "ingredients" and affect the final product.
Thus I become more than just the sum of ingredients; I metamorphosize into something completely unique. What I "taste" like is the totality of a process one cannot fully account for or control. And to un-bake it is impossible; you cannot reverse what is, essentially, a compositional change. You can look at the cake and try to guess what it will taste like, or you can taste the cake and try to discern the various flavors on your palate, be it a refined or ignorant one. But to un-bake it would be to defeat the process of creation, this multivariate expression that combines ad-infinitum beyond your grasp.
By changing my metaphor you changed the whole point of it, the whole essence of what I was trying to say.