Oedipus’s flaw was devinely inflicted (his curse/prophecy); attempts to thwart it (exposing him on the mountainside rather than, say, simply running him through with a sword at birth)* guaranteed it would result in the most terrible fashion.

The point was that Oedipus’ fate was sealed despite his “golden boy” greatness, not because of it.

* prophecy being prophecy, had he been killed at birth, that would have brought the kingdom to ruin: the gods’ will is stronger than that or any human.