There's no proof of your words , it's still a theory ..Show me where Gai invented the gates. People like Madara already have seen the technique. It is a forbidden technique because it was used in the past and people saw its dangers..
When you can get the names of all the characters of Naruto-verse, and i mean every single person in the story, from Rikudou's time to current, then ask me to state one. Otherwise, its pointless.
And most definitely not Gai and lee rofl. @ you mentioning Hashirama. Why would Hashirama bother with such a thing when he is beyond it? lol.
It is most likely a Senju technique, since it is a forbidden konoha tech.
I know gai can't defeat top10 but with 7 gates , he can defeat half of them while 8 gates definitely he can solo all of them but he will be dead after using it.Get over it. Your opinion usually stinks. He can beat a lot of characters but he also loses to a lot as well due to match ups and such and considering overall fighting prowess.
You really under rating him so greatly U_U