I see this happen a lot. I'll explain an exercise I'd like a student to try… the student will acknowledge, nod, and then this happens:
The student looks off into the distance… or at me… or, well... not quite at me, and not quite off into the distance, but looking very much like they are hypnotized. Then they attempt to play the exercise, they fumble, sputter, stutter, start over, pause, start over again, frown, hit a wrong note, pause again… you get the idea. But at no point does the student's gaze ever wander towards their hands or the instrument they are holding.
Invariably, I stop the student and ask them what they're looking at.
They say, "Oh, nothing really. I'm just trying not to look at the bass."
Invariably, I ask them, "Why?"
This part is prone to variation: Some students say they "heard somewhere" that they weren't supposed to look at the neck, others say they "just thought" they weren't supposed to look at the neck. But for whatever reason, they are convinced that if they look at the neck, they must be doing something wrong.
This is madness. You don't already know how to play; you're learning, and if you're learning how to do anything, the very first step in the learning process is… OBSERVATION.
This idea that you would try to coordinate your two hands, each doing different and unfamiliar things, while forcing yourself to look in a different direction for no reason… just... ARGHHHH.
This, I would offer, is actually an attempt to coordinate three things, because looking away from your hands while attempting to learn a digital pattern is so counterintuitive that it requires even more effort than just playing the exercise would.
Seasoned veterans, I am not saying that you need to watch your hands when playing that three-note Led Zeppelin riff you've known for over two decades. There IS merit in the ability to play something without looking. It's always beneficial to be able to make eye contact with the other musicians in the room, and it's an even bigger perk to be able to trust technical execution to your muscle memory while performing... and by that I mean PERFORMING as opposed to "just playing"; those moments when you're entertaining your audience with more than the sounds you make. I think these are definitely things to aspire to.
So there is merit to being able to visualize the fingerboard with your eyes shut... But in order to recreate that image in your mind's eye, you need to look at it a whole bunch with your ACTUAL eye first.
Observation is not a crutch. Deliberate avoidance of observation is. I did a little research to see if there's a word for that, and the closest thing I found is quite apropos.
"OSTRICHISM": "the deliberate avoidance or ignorance of conditions as they exist."
So don't be an ostrich; looking away from the fingerboard while learning to play is no better than sticking your head in a hole in the ground. Observe all you can. Doing it will not make you dependent on watching your hands… eventually it will give you what so many students find elusive: the comfort and confidence to play your instrument no matter what you're looking at, and no matter who's looking at you.