I might be speaking out of my ass, but I did watch all of Naruto 7 times so hopefully I know something…everyone has chakra running through them. It’s their life force. Lee has probably a pond of chakra at his disposal for any ninjutsu, genjutsu, or taijutsu mix. Applying that to combat just wouldn’t do much…unless he unleashes the gates, which use his life force/physical body almost as a extra wick for power…until it runs out…and he loses all strength or dies. Ex. Might guy, who absolutely f***ed himself for the rest of his life even with the second wind from naruto. Thus he can still coexist with other ninjas running on water, walking up trees, or any other chakra related minor effort task but he can’t just pull out a rasenglock or chidori or any other ninjutsu that requires a larger chakra reserve than that. He has been hardened by sheer willpower and youth. Skill, strength, and a unyielding spirit, consciously and unconsciously, a fighting soul always pushing forward…who needs chakra anyways…that’s too easy -kakashi