If that were the case then the prize should have been awarded to Yoshimuzi Ishino and Francisco Mojica (https://en.wikipedia.org/wiki/CRISPR#Repeated_sequences). This prize was specifically for a new method for gene editing.

Doudna, Charpentier, Zhang won joint prizes before for gene editing: Gairdner, Harvey, and Gabbay awards.

If Zhang was included in the Nobel prize, nobody would ask why he was included. But excluding definitely raises questions on why.