With no buffs or expert mods, theres no need for medium even for barbarrossa on historical date (june 1941).
40w light tanks is just enough to beat even max buffed SU.(300+divisions on field).
most AIs even USA will have piercing stuff almost at 42 or higher, in 41 theyre still all equiped with 36's stuff, which is beatable with light tanks.
Some equipment need rebalance, theyre super-expensive for AI, so the AI is scripted to stick with old stuff, because AI inst capable of fine tuning the production.
40w light tanks is just enough to beat even max buffed SU.(300+divisions on field).
most AIs even USA will have piercing stuff almost at 42 or higher, in 41 theyre still all equiped with 36's stuff, which is beatable with light tanks.
Some equipment need rebalance, theyre super-expensive for AI, so the AI is scripted to stick with old stuff, because AI inst capable of fine tuning the production.