With Time Erase, Epitaph, and the laws of fate, Diavolo finds himself near completely invincible. If a negative result were to show up on Diavolo's Epitaph, he could just erase that time and completely negate the consequence, changing his fate from negative to positive in just a single ability.
These factors make Diavolo one of the most terrifying villains for the protagonists to face, as any effort against him is almost always futile. Despite the best efforts of Bucciarati's crew, even going out of their way to find his identity, none had the ability to overcome King Crimson's predictions.
It isn't until Giorno utilizes a Stand arrow to pierce his stand, evolving it into a Requiem stand and completely reverting the effects of Diavolo's Time Erasing ability to point "zero", where Diavolo is finally defeated... and stuck in an infinite death loop.
Gold Experience Requiem Part 3, Chapter 147.