The light reaching the most centred wheat would barely be reduced in a 1mx1m vertical farm. Scale this to 100mx100m and it would be nearly dark without artificial light in the centre.
The whole point of this paper is about having high intensity artificial lighting on the crop. So-- I'm not sure what your comment means.
Ostensibly you would be able to do all sorts of shenanigans with light tubes for natural light and LEDs for artificial lighting regardless of the size of the facility.