no, it's just a useless skill. Or a useless goal, at least. Sure, it's impressive. But there is no shortage of reference and never a reason you cannot use one. So why handicap yourself? Certainly building more knowledge about anatomy is your goal. But you do that by working with reference. its like if my goal was to run a…
I'm pretty bad at reading people, so I'll ask directly, just to be sure that I understand what you all meant: is the ability to draw/sculpt a realistic human on the spot, without the use of references, something so hard and rare, that it's regarded as nearly magical?