The trouble for many geniuses isn't resources, but time.
Since martial arts and other cultivation methods differ, it's not about getting older and gaining more experience. The peak occurs due to biological mechanisms, only before one reaches between thirty-five and forty years old.
After that, they begin to gradually decline.
This led to, after the formation of the federation, the flourishing of Awakening Abilities, and martial arts increasingly becoming merely an auxiliary means.
After all, compared to interfacing with the World's Laws, Awakening Abilities, with all their miraculous effects, made martial arts seem utterly mundane. Not only was their peak short-lived, but they also required great hardship.
This caused many talented martial artists to explore Awakening Abilities. After reaching the pinnacle of Fusion, they abandoned martial arts and directly "Ascended in Spirit."
Martial arts thus continued to weaken incessantly.