You jest, but only parts of the brain are responsible for decoding auditory signals. It doesn't require weighted input from the whole brain to process these signals. In theory, one could surgically remove Brocha's and Werniche's areas, and they would function completely independent of the rest of the brain.

My understanding is that you cannot identify a region of chatgpt that identifies plant leaves and separate it from the rest of the neural network without destroying its function. In this sense, the entire set of billions of weights is required for each function that chatgpt does.

The brain has many separate components that function independent of each other, each of which is a fully functional neural network, all working in tandem.