This is correct.
The comet is (and was) not meant to counter Tank Destroyers as the Panther who have the sole role of countering tanks themselves.
It is meant to be some kind of a stock Tiger for the Brits meaning good AI and good AT (against mediums and below).
You also do not drive up to a supported Jackson with a Tiger.
It might have been overnerfed, but being able to defeat Panthers is not a good ground for complaints in my opinion.
Comparing a jackson and a tiger is not the same thing as comparing a panther and comet. Panther is a "tank hunter" not a tank destroyer, jagdpanzer is a tank destroyer, FF is, stug is, jackson is, su 85 is. Why is panther not a TD. Well because none of those other tanks either have the armor, health and OR speed to chase down wounded tanks and do it relatively safely because panther also has great escape helped further with a lot of popular docs abilitys (tact smoke, blitz). One of those above might have one of them but not all 3.
Also the TDs i mentioned above have almost 0 AI ability, panthers is not the best but it does have some the mg42 pintle is actually pretty good.
However I agree I dont expect it to out duke a panther as panther AI is not that great so thats the panthers good AT tank hunter niche. I just think comet was a bit over nerfed either in the penetration department or the AI department and it would be nice to be able to field it again but right now its just never worth it outshined by all the better tools that do their jobs more effectively.