Again, the most used mediums in the game are call ins xd.
apart from that, soviets still have their multi purpose mines, which stop any german tank.
You can still field a pz4 before the 85s hit assuming equal/close map control.
Fielding ZiS only against medium armor will be scarier and easier to decrew&steal. Plus Zis are a major mp investment. Many players in this patch could get away with skipping soviet t2 entirely, this will no longer be the case. Unless of course you're just stomping the ost player, in which case commander choice is irrelevant.
What's to stop ost from planting tellers for the 85s? Or OKW who has literally the exact same mine as soviets...
Your argument just doesn't really hold up.