She herself came out and said they were nobody. She searched her feelings and that was the truth she found, when people do that in SW they are never wrong. Now if the Rey parentage "reveal" is that they are still alive somewhere in the galaxy, that's not a big deal. Ben might have just lied about them being dead to force her to turn, but if she is the daughter of a "somebody" then that goes against the established story.
Part of her journey was accepting that there was no big secret to her abandonment, she was dumped in the desert by her deadbeat parents and they aren't coming back. That's what Maz told her in TFA and that's what she told herself in TLJ. To suddenly turn around and make her Han/Luke's secret child doesn't jive with that, even if it feels like JJ's vague teasing in TFA might allow for it. They stamped on that idea pretty hard in TLJ and it wouldn't make sense at this point. Why on earth would Han leave his child alone in the desert, especially after he split from Leia? How could Luke ever abandon his own child like that, especially as it would have been years before Ben turned and he lost hope in himself? It would require one hell of an explanation and I don't think JJ is capable of pulling it off.
