It's definitely too far a stretch to place it at the center - but for those who have experienced it, it is definitely a part of musical performance /for them/, and a not-insignificant part.
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.
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.