But why? I think when one practices stuff enough, you eventually lose the need to look at the fretboard
Apparently I look at the fretboard too much. I can play without looking just fine in one hand position. That's not the problem. I have to slow down when the next fret requires changing my hand position and about 50% of the time I'll miss it unless I'm looking ahead to see where I need to be. When I'm not looking, and have to move my hand more than one or two frets for the next note sometimes I'm right on it, and sometimes I'm not.