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I think what you are missing out here is how Axis can get rid of their vulnerability to artillery in the lategame due to dedicated anti-tank destroyers (Elefant, Jagdtiger, JP4) and their excellent synergy with anti-infantry vehicles (Brummbär, OKW P4, KingTiger, Tiger).
OKW infantry also becomes exceptionally strong in the lategame. It is easy to dodge artillery barrages when just having to micro 2 squads of Obersoldaten who terminate everything within reach.
This eventually causes massive attrition and eventually loss of experienced units for the allies, followed by a complete collapse of the frontline.
Btw, buffs should usually be apllied to units that have a strong underperformance and not because they are out of meta.
A general good approach to balance is: If you use the same unit over and over again - nerf it.