Humanism gave Azula nothing but suffering.
Interesting point. Although throughout almost the entire series Azula literally tries not to kill or at least maim her enemies. She gets absolutely nothing for this humanism except problems.
Azula did not intentionally kill Iroh, but only wounded him in the shoulder with fire.
Azula had excellent aim since childhood, so she wanted Iroh to get away with just a wound. Although she could have shot him in the head.
And this only allowed Zuko to master lightning redirection.
She spares the Kyoshi warriors and Appa. Although Aang's animal is a unique vehicle, the destruction of which would clearly deprive the Avatar of his exceptional mobility. And the Kyoshi warriors are ballast that must somehow be transferred to the Fire Nation guards, while still fearing that they might try to escape while they are being escorted to Fire Nation territory.
She spared Katara, which would later greatly ruin her life.
Aang was only able to survive because Azula spared Katara.
So that later he will be able to gut her father's soul.
She spared all these people. Which also gave her nothing but problems. Because as expected, they simply ran away.
She tried to redeem Zuko and even dragged him to the capital in a blaze of glory. And no. The whole scapegoat theory is crap because:
The Avatar is not Azula's mission at all, she doesn't need to report on his condition at all. The Avatar is Zuko's mission and he must answer for it. Accordingly, Azula has no reason to look for a scapegoat at all.
Zuko knew about the spiritual water, not Azula. Azula didn't know at all that people could be resurrected. And she couldn't have known. That's why she acted as a person who is confident that the main threat to her and her country has been eliminated.
Azula is obliged to lie to Ozai that Zuko killed the Avatar precisely because she promised Zuko that she would return their father's respect to him. The reports that Zuko only had a good fight with a water peasant are absolutely not enough for this.
In fact, Azula became Zuko's scapegoat because any appearance of a living Avatar in any case turns her into a liar who announced that the living Avatar is dead. She is the only witness to this death and she lied to Ozai.
The problem isn't even that with Katara, Mai and Ty Lee or a crowd of Dai Li could have helped her. The problem is that after the battle of Ba Sing Se, absolutely nothing stopped Azula from getting rid of both Zuko and Iroh. And that would have really solved her future problems. Not to mention the hundreds of Fire Nation soldiers who died because of it.
By the way, in this same episode Azula spares Iroh for the SECOND TIME. And who would have thought that nothing good would come out of it for her again.
Against this background, the fact that she spared her friends already seems insignificant. Because this Chekhov's gun simply did not have time to fire.
This is really very symbolic. Azula lost precisely because she was not a monster. If she were exactly as her haters portray her, she would have won!
And this raises the key question: what if, for her own good, Azula had to become a monster?