I don't disagree that training helps, but all of Kakashi training was useless until he was given a power up through Obito powers, that's really the issue, no amount of training will make up for the gap of having special eyes or super chakra. Only exception being Guy who could go to that level by sacrificing his entire life force.You have that reversed. Kakashi's done more with these skills than Obito ever did. He's got powers lesser than Naruto and Sauske and is still by far the strongest person on the battlefield. That's not natural advantage, that's skill, hard work and experience. Kakashi's got all those in spades. You give Obito's powers to anyone else, including Obito himself, and they'd be nowhere near as overpowered.
Naruto 689
Woah, Kakashi can actually do stuff.
And did sakura do something too? that's amazing
Sakura had the ability of being completely forgotten, allowing for a stealth attack.