Although by no means unique to Japan, this is typically an Enforced Trope in many corners of Japanese media. It is enforced in order to uphold a core Japanese value: the belief that no one can be strong alone and, thus, juniors must rely upon their seniors.
Japan is a highly "Confucian" society and, thus, tends to divide persons into an ever-present "hierarchy". One of the core values of said hierachy is a constant veneration, and deference, to one's seniors. Those who came before you know more than you do, so their wisdom and generosity is needed in order for your continued growth. This is known as "amae", or a relationship wherein one person relies upon the goodwill and kindness of those above them. A person who does so is thus doing "amaeru" (verb). Amae and amaeru are considered one of the most intrinsic values of being a good Japanese citizen.
You can tell this is about to happen when the hero's tricks become So Last Season or they suffer a No-Holds-Barred Beatdown from the next step up in the Sorting Algorithm of Evil. This typically happens to reinforce that this is as far as the individual (no matter how talented) can go on their own, and thus the generosity, benevolence, and wisdom of their seniors are to be respected and revered. In many series, this cycle is nigh-infinite and neverending to reinforce that no one should ever grow full of themselves or sure of their own power.
