“… maybe that makes eye contact the very essence of music.”
…tell that to Ray Charles and Stevie Wonder!
Pop is a different field. Bands are more manageable because the individuals all have separate lines and are supposed to be listening to each other. Which is how blind musicians like Stevie Wonder signal changes through their playing rather than through eye contact.
In an orchestra you have entire sections of somewhere-between-6-and-24-more-or-less people all trying to play the same lines while facing in the same direction, while another section plays something else next to them and/or behind them.
Keeping everyone together is a harder problem.
Yes and no. I agree that it's very difficult for classical musicians who are completely blind, but there are talented musicians who are legally blind and make use of assistive technology. I know an oboist who plays very well in orchestra despite only being able to see two or three bars of sheet music at a time.
Bands are more manageable because the individuals all have separate lines and are supposed to be listening to each other.
I think the issue is the other way around really. Yes, the musicians in a band all have separate lines, but it's all very coherent -- a melody and some harmony. In symphonic music you might have 24 violinists all playing the same notes, but that's the easy part -- the hard part (and where you really need a conductor) is when one melody is bouncing between the 1st and 2nd violins (with supporting harmonies in the lower strings) while a counter melody is being played by the clarinets and French horns and the trumpets are furiously counting 57 bars of rest before they interrupt in 3/4 time.
There might also be some unexplored areas in this article, with regards to the role of eye contact in /improv/, especially jazz improv and the like. There's a lot more communication that occurs both through instruments and non-verbal cues in that setting.
When I've played keyboard in a group setting, I've noticed I'll use eye contact to let someone know that we're feeling out-of-sync - perhaps in tempo, for less experienced groups, or to mark a chord transition or harmonic opportunity they're missing, or to encourage them to push a bit more in a section where they're withdrawing too much.