Why isn't the Puma on here? I lose more armor to Puma than anything else on this list.
Because in controlled environment Puma would lose even to KV-2
No, indeed my logic is spot on. I'm afraid it is you who are mistaken. A tank destroyer is a tank specifically designed to specialize in destroying tanks. A Tiger, while exceptional at destroying tanks, was designed to have multiple roles as a heavy tank, i.e., it is not a tank destroyer. So yes, I am telling you that the Tiger is not a tank destroyer in that sense.
The StuG series, for example, is a series of assault guns. There were many variants of them. Some were infantry support guns, howitzers, etc. The ones outfitted with high velocity anti-tank guns are tank destroyers because they are specifically designed to destroy tanks, even though they are assault guns.
Also, when you say tank destroyers are designated as such by their role on the field and not their design, you don't seem to understand that tanks are designed to have a role. They don't just randomly slop tanks together and go "Well, let's just throw these on the battlefield and see what they excel at."
Ok, maybe I was not clear enough. You have TD designed to be TD but you have also plenty of universal units, mobile howitzers and stuff like that which can be named TD.
Do ISU, Tiger, IS2, Tiger II, Panther are not Tank Destroyers? Of course they are.
It seems that your condition to become TD is lack of turret (except Jackson) and no AI abilities.
Which unit can bigger threat for your tank? SU85 or ISU152?