Since Dragon Ball is exist. Kishi take the Idea from there for level up idea of characters after certain arc is ending and new arc is entering. And don't asking about logic here
Even DBZ has inconsistencies so??
They get hurt by rocks Lmao.
Anyway, mangakas don't draw shockwaves always as it gets messy at times. Actually in part one many characters were creating shockwaves while fighting too. U_U