The acknowledgement of similarities is all I'm pointing out. Judes writings appear to have been influenced by Greek mythology via the book of Enoch.
"That The children of the gods should not meet with wretched mortals, seeing their feet in their own eyes, But that the blessed God's henceforth even as aforetime should have their living and their inhabitants apart from men. But on those who were born of immortals and of mankind verily Zeus lay toil and sorrow upon sorrow."
-Hesiods Catalogues of Women and Eoiae.
Even beyond Hesiods theogony, and parallels of titans buried in rock and stone, chained up in Tartarus, and covered beneath a gloomy darkness, the nephelim themselves were described as giants, much like the Titans. There are references to children of God mating with human women, and Zeus laying toil and sorrow upon the interbred children. In instances where the gods did not keep to their proper dwelling.
The narratives are not identical, but the evidence for influence remains.