You must have a way to identify each individual ballot form so that it is scored correctly, especially if the ballot is sent to a large centralized location for processing such as was done at the State Farm Arena for Fulton County.
There's no way around that. Within a single county, there could be dozens of different ballots with differences in offices and initiatives at the township level.
I suspect that the better and stronger analysis of the facts is that the lack of ballot codes on so many ballots in Democrat counties may be a sign that such votes were fraudulent.