ENT: "Demons"/"Terra Prime" did confirm that a human-Vulcan hybrid child would require medical and genetic intervention to achieve. And DS9 said it "wouldn't be easy" for a Trill and a Klingon to have a child, implying the same. On the other hand, there have been cases of hybrids apparently being conceived "by accident," like Alexander and Ziyal. I wouldn't call that "compelling," I'd call it misogynistic. A desirable woman as an animalistic beast? Female allure as a lethal temptation for men? That's steeped in Roddenberry's generation's sexual hangups and centuries of cultural demonization of female sexuality. Considering that Roddenberry's own treatment of the women who worked on his shows would be unlikely to pass muster in the MeToo era, the recurring tendency in his work to blame women for being irresistible creatures luring good men astray (see also Nona, Ilia, and the opening narration of his 333 Montgomery Street pilot with DeForest Kelley) comes off as making excuses for his own sexual excesses. That doesn't add up, since Sargon's people were colonizing the galaxy well before Homo sapiens evolved. 600,000 years ago, our ancestors would've still been H. heidelbergensis, capable of controlling fire and using primitive tools, but not yet capable of humanlike speech and not yet creating art or abstract symbols. Of course evolution in real life doesn't work the way Star Trek portrays, but neither does relativity, quantum physics, temporal physics, force field dynamics, linguistics, etc. Humanoid aliens, like warp drive and universal translators, are a deliberate break with reality for the sake of the narrative. It works that way in the story, regardless of how it works in reality.