Soviet, USA, OKW have the SU-85, Jackson, Jagdpanzer IV with 60 range each to handle heavy tanks. Wehr doesn´t have a 60 range AT vehicle. If you go Wehr and don´t go for a Tiger/ Elefant doctrine, you have the Panther. Touch the Panther and you will see increased call-in meta.
Teller mines, TWP on PaKs, even on StuG-G and no, IS-2 doesn't reliably wipe infantry or PaKs, out of all tanks only T34 is worse against infantry then IS-2.
All factions use different means to fight off heavy armor, 3 of them have 60 range TDs, 3 of them have potent AT guns, 3 of them have handheld AT that works more or less and so on.
Raw firepower isn't the only way to deal with heavies, which every soviet player can tell you from the first day of CoH2 and ost definitely does not lack in variety of non doctrinal options to deal with heavies.
And who talks anything about ost panther?
If anything, OKW one arrives way too fast.