Stug = meant to counter medium tanks.
Panther= meant to counter heavy tanks.
/thread
I don't really like this argument. It's true, but it's bad design. This means Axis not only have to spend resources on one of the most expensive stock tanks in the game, but they also have pay for transition cost. They might need a Stug to survive the mid game, then have to get the Panther on top of it. It's the same for the Jagdpanzer IV, although that one is better late game because 60 range. The Allies can fight much more cost efficient because their TDs can fight every single type of tank. They make one to keep the mediums at bay, but then do not have to spend anything extra when the enemy switches to heavier tanks. This gives Allies a big advantage.
IMO tank destroyers should get high accuracy, good pen but mediocre ROF so they can reliably keep heavy tanks and heavy TDs away while not being very good against mediums.