Benders? I'm sorry, I'm not familiar with your terminology. Are they like, elemental attack users or something?

[ She considers the question before answering. ]

It's not really either or. Anyone can learn it as long they have Chakra. However, that's only for sealing items. I can make prearranged scrolls for just about anyone to use as long as they have good timing skills, but I guess I can temper with the activation requirements for those not too skilled with timing. [ woohoo for canon vagueness! ]