i thought there were 7 chakra points?...
and i dont think he messed up, the gates are actually there for gradual increase of muscle power due to opening the chakra flow
in real life, ppl cant use more than 20/30 % of there total muscle power ( even how much you would strain, you wont go higher) because of limits in the brain, if you go higher you can damage yourself, BUT if you were able to go higher, your strength would increase, drastically..... thats actually the gates for ya there, except for no human can disable the limit, and even if 1 could, you couldnt increase it in 10% each time
and for the whole chakra thing, i just think he didnt want to go for too much reference to dbz, so he altered it abit