Yeah, the 8,8cm/71 is really really good, but here's the thing- it's only really really good when it's shooting the good ammo- the PzGr 40/43 rounds. Gee whiz, will you look at what piece of war materiel was never in long supply? PzGr 40/43 rounds. Or, for that matter, the other AP round for the gun, PzGr 39/43.
You know what they had? PzGr 39. Guess what else fires PzGr 39? Tiger I and the 8,8cm/56. Gee whiz, JMPer, what happens when you shoot a KwK 36 round out of a KwK 43? You get KwK 36 levels of performance. The Leveling Effect is, for good and ill, a normalizer. Without prior mention that these were, say, Personal Guard of Hitler SS-tanks, well, they get normalized down to stock. And stock Konigstiger probably wouldn't beat the Abrams under leveling effect.