I refuse to believe anyone who says they can't draw like that, because all it is is completely letting go of your head, and drawing in a stream-of-consciousness style that's composed of your hands almost instinctively drawing lines and dots and shapes. I find it's basically the best way to relax, though I haven't really taken the time to do so in a long while. I probably should.
I know the purpose and I know the "technique", but I have a hard time even drawing clear lines when I am not thinking ^^
My strongest moments are when I exactly know what I want to draw and can think about every line beforehand.
Letting go of my head almost always results in weird, grungy, restless linework, never in drawings as clear and complex as yours up there.
Here is an example of how grungy my traditional drawings are (when not using a reference) even when I do plan ahead:
(If I should start using thumbnails again, just tell me)