First of all, in point #4, you don’t need the asterisk by America, since the Chozen/Daniel confrontation took place in Japan.
Second, if you want to talk about lasting impact, you have to take into account all the subsequent Karate Kid movies, and if you do that, almost NOTHING post-Crane Kick had any impact. Daniel continues to be a naive schlemiel, getting bullied by whatever alpha dog happens to come up to him, then getting JUST ENOUGH training from Miyagi to triumph (though in reality, Miyagi never explicitly instructs him in the move — crane kick, weird thing with the drums, the kata — that ultimately lifts Daniel over the top, which is kind of dickish of Miyagi), and then they hug it out.
If you think about it, things get markedly WORSE for Daniel post-crane kick. Ali leaves him, he meets a girl in Japan who he can’t be with, he spends his mom moves to Fresno, he spends his tuition money opening a bonsai tree shop, and gets friend-zoned by the cute redhead from the pottery store.
It was basically the equivalent of the tsunami waters of his success receding and reestablishing the coastlines of his lameness.
By contrast, let’s say he doesn’t land that crane kick and loses the tournament. It’s not hard to imagine a scenario where: Johnny still feels bad about sweeping the leg and begins to respect Daniel and stops being a dick to him, the Sensei loses all his students and is charged with abusing minors, and Ali goes full-on florence nightingale syndrome and decides to care for Daniel day and night and never meets the dude from UCLA that she ran off with. Plus, she never wrecks Daniel’s car then either. Winning that tourny had to be the worst thing to ever happen to Daniel.