Originally posted by burritobandit 
Yes, it's in relation to the size of the kite.  Bigger kites will turn much slower on smaller bars, because there isn't as much 'throw' on a small
bar.    People keep smaller bars for smaller kites so that they won't oversteer the small kites.    
 
This is an extreme scenario, but for visualization purposes only: 
(WARNING: DO NOT ATTEMPT TO FLY YOUR POWERKITE WITH A TOOTHPICK) 
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