So does instinct exist or is it a theory, that explains the unknown and seemingly unexplainable, similar to spontaneous generation or god?
Interesting question. But, a poor point to argue for god.
A baby instinctively suckles when hungry and offered the opportunity. I think just about everything else, for humans, is learned.
So, when someone tells you a new device interface is intuitive, you can use b00bies as an appropriately humorous dismissal of the claim.