I guess it is called the process of learning. They use to switch the neutrals going to lights--- who knows what they were thinking. Knowing what we do today we have learned that it is bad and dangerous to do so.
One of the biggest dangers with switch or fused neutrals was it energized the shell of a lamp holder when the neutral opened, current from the hot flowed through the load to the shell, also turning off the circuit doesn't remove the potential to ground hazard, so for the most part it is a shock hazard.