Hmm, no. I know that wikipedia is not the authoritative resource, but I think their definition for MBT is pretty good: a tank that had the firepower of a super-heavy tank, the armor protection of a heavy tank, and the mobility of a light tank, in a package with the weight of a medium tank.
The russian MBTs got into the heavy tank bracket of WWII equivalent only from T-72. Don't forget the prototypical MBT, PzKpfw V Panther, was 44t while still being considered a medium tank. Almost same weight as the heavy soviet IS-2 (46t) which was a heavy tank. The russian turret design was more weight efficient than the German ones, so generally the russian tanks of WWII were lighter (and faster) than the German equivalent.
Tanks went through a major growth spurt during WW II, especially German and Russian. The definition of light and heavy tank was fluid. The M-26 Pershing was a heavy tank weighing in at 46 tons. It entered service at the end of 1944. The M-46 Patton entered service in 1948 weighed 48 tons, it was classified as a medium tank. The M-47 was classified as a Main Battle Tank though it was only a moderate evolution of the M-46.
The British Centurion was classified as one of the first MBTs at 50 tons.
The distinction between a medium and heavy tank is more about mobility than weight. Heavy tanks in the WW II era were usually slow, ponderous tanks and medium tanks had much better mobility. The Panther was not as well armored as the Tiger, but it had a better power to weight ratio.
Basically the idea of having heavy and medium tanks was kind of redundant by the end of WW II and the Main Battle Tank was what came out of merging the two classes of tanks. Tanks have gotten massive over time and put heavy tanks of the WW II era to shame. Western MBTs are much heavier than Soviet/Russian designs. Most western tanks don't have an autoloader so they have an extra crew member in the turret and that requires the turret to be larger, adding to the overall weight.