All these people defending it as some inherent technique that was hoarded by the greedy elite. Knowledge is more accessible than superpowers. Concrete ideas can be transcribed and stored, then passed around and used without expending it as a limited resource.
Superpowers, even if they're rooted in shit like Chi/Chakras/Spirit Energy, would still fundamentally vary on a person's experiences, knowledge, and aptitude. Spin it how you want, but it took somebody that had matured on these points to use any rare abilities in ATLA.
Toph's metal bending, Hama and Katara's blood bending, and Azula, Iroh, and Ozai's lightning bending, all came from having exceptionally unique life experiences/upbringings that created a need for them to be strong benders, knowledge of bending accumilated over time, and an aptitude for their rare abilities. Zuko - the most main MC behind Aang in ATLA, had the harsh life experiences and the knowledge from Iroh, but no aptitude to learn lightning bending.
We don't know much about the lives of the factory shmucks in LoK. They may have the inherent aptitude and accessible knowledge, sure, but also life experiences comparable to people drastically affected by war that would motivate them to reach the peak of their bending potential? Either the Avatar superpowers are rooted in some consistent methodology, or LoK is poorly written. Idk, which does /co/ like to routinely bitch about, again?