Before... Black Zetsu's mother emerged from her seal, Chakra was a product of spiritual energy and physical energy mixed evenly together.
And after the Sage of Six Paths created the Ninja Sect, he spread chakra throughout the entire ninja world, driving the evolution and development of its unique order.
Just think about how tiny and adorable the tailed beasts were when they first split apart... Yet after a thousand years, every one of them had gotten fat!
Therefore, Chakra could grow. It was not fixed, at least not until it reached a critical point!
And after the Sage of Six Paths spread Chakra throughout the ninja world, practically everyone could now extract Chakra. The only differences were how much they possessed, or whether they had a bloodline limit.
It could be said that Chakra was an ability almost anyone could refine. Some had great talent and abundant Chakra, while others had poor talent and little Chakra, but through hard work, they could still become excellent genin specializing in taijutsu.
After all, not everyone was an Azure Beast!
Although low-level ninja who relied purely on taijutsu were greatly limited, they were still ninja overall.
And in the Land of Grass, they did not need to carry out missions or assassinations. As long as they could refine Chakra or understood some Production Ninjutsu, that was enough.
Therefore, because of Chakra's special nature, geniuses could emerge even among civilians. From one perspective... this was also a special path to advancement?
Speaking of which, Kaguya Otsutsuki and Black Zetsu, mother and son, really were wasteful. Since Chakra could grow, why make things so troublesome?
Wouldn't it have been better to simply start a company and harvest Chakra slowly?
You had to know that once chives were cut, all they needed was some water, sunlight,