Bullshit on one unit does not excuse bullshit on others.
But even if we accept that the JT can fight team weapons:
There is a huge difference between the JT pushing back a single team weapon (probably an ATG which is supposed to counter it) that is a third of its price and population and the ISU forcing back the Ele/JT at a similar price level. Especially since this could have the side effect that an ISU that is capable of defeating the Ele/JT would slaughter the Panther and anything below.
you are underestimating the jagdtiger barrage - its basically a steroid version of the brummbar bunker buster barrage
Asides from the fact that the jagdtiger slaughters all armor that exists in the game, it counters any and all allied armor that can be found AND it can take care of team weapons (either AT gun walls, or clean MG/bunker nests) for your already very potent infantry to move forward
the isu-152 already defeats panthers and below with the alpha damage that it provides, but obviously its unfair that you should kite 230 fuel heavies and flank the isu-152 with panthers, you clearly must be able to face tank the damn thing!!!!111!!!
Jokes aside, they shouldn't have nerfed jt/ele counters and wondered why each and every axis team comp in team mode is heavy TD stall with a dedicated lefh/panzerwerfer spammer