More often than not, it may have also been Disney's predilection towards rotoscoping human movements that were "hard" to draw realisitically. Dancing, walking - just noticed the windmill in The Aristocats last night. There's no end to it, and occasionally you'll see clips from old b&w films they "studied" to do the drawings...
hihihihihihihihi
http://www.prodisney.ru/index.php?page=clones.php
The link you posted is the same as in the entry though, same thing with the story over at BB.