I've used Emvoice on a track, writing lyrics and melody specifically for the AI robot to sing. Aside from some pronunciation issues (she struggled with the word "maggots"), the song turned out fine. I wasn't trying to pretend it was a human voice; I was just seeing what I could get away with. The track appeared on an album that also featured several female vocalists doing everything from lead vocals to very processed ambient sounds, so the Emvoice track fit right in/didn't stand out.
And I know the original post is to do more specifically with a certain commercial brand of pop music, but in the wake of Robbie Robertson's death, I'm all the more certain that humans will always resonate to the sound of other humans being human. If AI can generate its own version of The Band, well, I'll be happy to give it three minutes of curious ear time. Meanwhile...