I believe one of the essences of Chinese martial arts is controlling your opponent's balance through striking and sensitivity
... which means thereotically you shouldn't have to see your opponent to control them.
Not to say the eyes are useless -- that's just absurd.
However, a reaction from your spinal cord/nerves is alot faster than a reaction which you had to 'see' and process in your brain.
Don't know about blindfolded sensitivity as a goal itself, but it shouldn't be too difficult for someone who can apply their stickiness/sensitivity at a competent level.
Personally I have found that closing my eyes during free grappling and push hands sometimes stops me from being distracted by my eyesight. Too much mind