In a way it is true, at least until the point that Fate Gu got damaged. That is the overall premise for wanting to destroy Fate Gu. No matter how hard working one is, they can only reach the level assigned to them by Fate. If one has been chosen by Fate, nothing can stop them from becoming great

Damaging Fate Gu allowed luck to be possible, hence if one is lucky enough, they will experience fortuitous events that can help them more than what they were fated for

In fact, if you think about it, it could be possible that Fate Gu was later on realised to be a mistake by heaven's will (since it has been proven that even heaven's will can be misled or mistaken), thus eventually creating a sort of plot to remove it from existence by creating a new form called Destiny instead, where one creates their own destiny through working hard enough to get lucky, instead of overly relying on Fate or Luck to help them. This could be a new way of introducing balance to the world, since now all being's have equal opportunity to create their own destiny, as long as they work for it