He is saying live is both visual and auditory. Your brain puts the two together live to create localization. I don't know halls you frequent but I can clearly hear depth and instrument localization to a pretty high degree...even with my eyes closed but it is enhanced by visual confirmation.
Same with me. If you sit close enough to the stage, certainly depth and localization is all there. Once you sit far away enough so that the contribution of reflective sound overtakes that of direct sound, then indeed it becomes 'one big mono'.