Those are techniques
What king has is just body function. Like hair growing on your head. Saliva in your mouth. Difference is king can manually on/off it
It is used as tool in combat.
It's just like Luffy's fruit or the Diable Jambe. They are bodily functions - the passive rubber properties or the flames. But you need to train it and utilize it in a way in order to master it and efficiently use it in combat.
An average Lunarian won't be a YC1 lvl fighter.
PS. Electro is also a bodily function for minks. And King also has flaming attacks like Andon and the DJ kick.