Ah, but perhaps you and I are speaking of different sorts of failure.
Homosexuals usually succeed at getting their satisfactions, one way or another; they often succeed at corrupting institutions. But they do not, and cannot become the natural norm, nor can they supplant what is actually the case about reality ontologically. Homosexuality is merely a dead-end proposition with a very pervasive habitual force to it. Like Ebola it burns itself out.
They evidently didn't need to be the norm to be useful to the royal slave-breeding wannabe god-men for whom they served as the (XXY/Androgen-Insensitive?) keepers of the keys to the kingdoms of Babylon, Egypt, Rome...
In fact, it's reasonable to observe their abnormality was a desirable feature - one presumed to naturally preclude the eunuchs from using the powers vested in them toward the propagation of their own lineages.
Obviously the devious nature of their abomination and survival instinct was underestimated by their masters.