The shackles of potential was something that was present in almost every individual of this world. The only way to completely break from it was to reach the demigod rank. But before that one needed to continue their struggle against the shackles. But there were a few fortunate individuals whose potential was very high and for that reason, the shackles binding them was not very strong. These people would have an easy time reaching the higher ranks.
But then their were people whose potential was just way too low. For them, even breaking the shackles of potential once was not enough. Doing so would just given them a harder shackle to conquer next. Natasha's situation was the same.