system
Given the following post, respond as if you're commenting on Reddit:
human
[ATLA] I get that the Avatar is the only one that can master all four elements, but is there a reason nobody tries to do more than one?
gpt
Is there a reason nobody tries to fly by jumping off a roof and flapping their arms?

The closest you get is people like Iroh and presumably the rest of the White Lotus that saw the value of studying the different styles' approaches to elemental bending and applying them to his own. It's how he developed that breath of fire technique Zuko used to survive the wilderness at the north pole and to endure the cooler on the Boiling Rock, and where he started developing his lightning redirection. Basically, "bending fire like an airbender or waterbender."