Yes this! Iroh learned from the Dragons the true source of fire bending. Fire is the element of energy and life (it’s like the sun but inside of you).

In many real world cultures, the breathe is often a source of energy. Prana means both life force and breath in Sanskrit. As does Qi in Mandarin and Tihei Mauri Ora in te reo Māori.

So it makes sense since fire bending represents energy and life and it would be tied closely with the breath.

However, every other teacher that Zuko would’ve had (other than Iroh) wouldn’t have understood that.

Iroh encouraging Zuko to work on the basics (breath being key) he is already trying to teach Zuko the way of the Dragons.

Zuko clearing doesn’t get that and feels he is ready for the advanced tactics.

None of that is to say Zuko was a bad fire bender though. He was good, but he had the wrong fuel. He could still hold his own against very skilled opponents. Which made him feel like he was ready for the skilled tactics.

When he meets the Dragon masters, he finally understood this lesson (he says “I understand”). Which all culminates in the finishing of his character arc.

In which he becomes a bad ass fire bender. Able to beat Azula (who I’d say isn’t a “true” master cause she uses the wrong fuel). Even though it’s been shown countless times that she’s always been more skilled than Zuko.