Also, vast portions of the human brain are dedicated to the visual cortex, smelling, breathing, muscle control... things which have value to us but which don't contribute to knowledge work when evaluating how many parameters it would take to replace human knowledge work.
I wonder if our brains and bodies are not all that separate, and the intangible features of that unity might be very difficult to quantify and replicate in silica.
"If our small minds, for some convenience, divide this glass of wine, this universe, into parts -- physics, biology, geology, astronomy, psychology, and so on -- remember that nature does not know it!" -Richard Feynmann