It makes perfect sense.
There is optimum power level. Balancing units in non optimum power level might have become easier (after of countless buff to some unit) but it is not "practical".
I think I finally get what you mean here.
Say we've got five squads, one of which is worse than the others.
Squad A: Cost 50, Combat Value 100
Squad B: Cost 50, Combat Value 100
Squad C: Cost 50, Combat Value 80
Squad D: Cost 50, Combat Value 100
Squad E: Cost 50, Combat Value 100
Cost is how much you pay for it, Combat Value is how good it is.
To most people, the solution here is obvious: raise Squad C's combat value to 100. Why would you quadruple the work by lowering A, B, D and E to 80 instead? It makes no difference when you look at it this way.
However, what I think you're looking at is this:
Squad A: Cost 50, Damage 8, HP 12
Squad B: Cost 50, Damage 8, HP 12
Squad C: Cost 50, Damage 4, HP 12
Squad D: Cost 50, Damage 8, HP 12
Squad E: Cost 50, Damage 8, HP 12
Here the two balancing routes are raise C to Damage 8, or lower A, B, D and E to Damage 4. However, when expressed this way, there's a difference: the 'buff one' route results in a higher ratio of damage to durability than the 'nerf four' route.
In summary, when you say you want to nerf Volks, Penals, Rifles and Sections instead of buffing Cons, you're talking about their damage, not their durability. What you want is an overall decrease to lethality in infantry combat. If you buffed Conscripts's damage and buffed everyone's durability, you'd get the same result.
Am I correct?