This is how I understand it…Interesting, but I've seen videos on YouTube of someone asking a non-verbal autistic person a simple yes or no question and they quickly tapped in yes or no on their keyboard without looking like they were thinking about it. What stops them from saying yes or no, or even shaking their head or nodding?
I think it’s like asking you to use something other than your most instinctual way to answer a question. For you and many others, it sounds like a verbal answer is the easiest and the most natural.
For some of us, it is not as instinctual to express ourselves verbally because it is so taxing and can be anxiety inducing. Processing speech (receptive and expressive) and engaging the motor skills to talk can be taxing to some brains and most humans instinctually conserve energy resources for survival. So, learning and acquiescing to verbal communication takes more brain power for some of us.