I think even this gives too little credit in a way. Why were the walls whitewashed? To grow less mold and generally stay cleaner. That's the only why for doing

I think even this gives too little credit in a way. Why were the walls whitewashed? To grow less mold and generally stay cleaner. That's the only why for doing the action, and it seems to have been perfectly well understood. The only thing the modern biochemical understanding does is tell us why this worked. At best this can help us find more effective methods, but it doesn't really add anything to the practice. Put another way, if you were put back in time, what would the most effective means of accomplishing this goal be? Probably the same lime whitewash actually used.