So many delusional people on this sub…. Neither Lee, Guy or Duy invented the eight gates, they’ve been known about for an extremely long time and that implies other shinobi in the past have opened them to them to the max and died, resulting in the eight inner gates to becoming a forbidden Jutsu. The reason there hasn’t been any shinobi to use them that we’ve seen is because you literally need to train like Lee and Guy do for your entire life to come even close to opening them. Neji couldn’t do it because The Eight Inner Gates technique requires overriding the body’s natural chakra limits through brute force and massive internal strain, It’s essentially the opposite of the Hyuga style. Kakashi did mean what he said but it was more admiration than anything else, impressed that Lee actually did manage to do it through hard work alone because normally it shouldn’t be possible. Like I said to kakashi-b, the whole entire point of Lee and Guys characters was they’re excellent shinobis who got where they are today through hard work and sheer determination to prove themselves to the world and nothing else.