u/Accurate_Spring_3249

I think what makes the Avatar so powerful isn't just his multiple bending, but the fact of the mindsets he gains from those said bendings, it has been stated before that a bender becomes a better bender if he learns the philosophy behind other bendings, even if they only have one.

Air bending teaches to be free, sensible, fast as the wind and be able to move like the wind

Water bending teaches to be flexible and adapt to any situation and not be rigid

Earth bending teaches to wait and listen for the right moment, not rush ahead and when the time comes, you stand ur ground

Fire bending teaches how to control such raw power and not let it consume u

And the Avatar encompasses all of those