I'm not sure you realize, but Panther is one of the very few non-doctrine tank that can wipe AT from the front 1v1.
OKW can counter with cheaper JP4, and while WM doesn't have expensive TD, can go for Panther to dominate AT or just stack up the cheap stug. It does come with (comparably) low pen, but it has very gigh Fire rate so its dps is pretty decent enough to counter Comet.
Your not going to seriously suggest a panther wiping a at gun is a viable or realistic scenario, why even mention this ?
Ostheer is weird in their tech that the panther is gated behind another layer of tech, I dont know why your so against a slight reduction in armour it would still have so much to offer..