Well, but if the Tiger II could blow a Sherman up in 2-3 hits (or 1-2 with the 10.5 cm KwK), while the Sherman needs some 5-6 rather than 12, the game won't be broken. Look at Tier 1 and 2, where all tanks could shoot each other in 5-15 seconds if all shots count (and armor plays a great role here) and the game is fast and fun.
Then there's the fact the Tiger II's armor is very resistant (frontally immune) to 75 mm shells while the Sherman ain't stopping anything bigger than medium velocity 57-76 mm rounds, another self-balancing mechanism tanks have.
Edit: A King Tiger could in fact destroy a Sherman in 2 hits using an 88.