Muscle memory is not using some brain power as the GP says. Once you are used to it (2-3 weeks), it feels very natural, I think "Oh I need to change the end of this sentence" and my fingers will take me there. It really is an extension of touch typing.

Gee I got to the point of feeling natural after 2-3 months...

He's describing how it feels to be a good vim user, not how it works in reality. A great tennis player might say "I don't think about how to hit the ball, I just think about where I want it to go and it goes there", and that would be reasonable. Then you come in and say no that's gibberish, unless he has a spinal cord dongle hooked up to a robot that hits it for him, he has to be thinking about doing the actions, they're not automatic after all!

> unless vim comes with some sort of spinal cord dongle

cerebellum is largely responsible for your muscle memory but premotor cortex stll needs to initialize those commands (what keys to press) then the cerebellum adjusts the precision i.e touch-typing part of it guess...

Do you think about each key you want to press to type a sentence?

I expect not. Vim, for those that use it, is merely an extension of that.