I disagree. The artist had to draw a believable figure, taking into account the pose , and position of the figure, perspective etc. They had to manually perform the 'tweening' process that in 3d is all automatic. It took incredible amounts of time , and all had to be redone if the director changed his mind.

 

What they did have was the ability, by drawing the figure to do compression and stretching of teh figure. The 'happy choo-choo'  bit, which is not realistic , but gives cartoons a special feel.