That's because commandos go against armies with weapons designed to kill 5 and 6 model squads and storms go against armies with weapons designed to kill mostly 4 man squads and have a singular examples of 5 and 6?
There are no small arm weapons specifically designed to kill 5 or 6 models....
There is no issue here.
Yes there is
So are conscripts and osttruppen.
Or grens and tommies.
Or shermans and P4s.
Or HMG42 and maxims.
Or obers and LMG paras.
Or M15 and 251 flak.
Or kubel and M3.
Or Tiger and IS-2.
Yet they still perform vastly different and have their own unique advantages and disadvantages.
Another derail attempt with issue completely irrelevant to storm troopers.