So I was reading through WOBs and found this one.
The time it came out lines up nicely with the time he was probably working on it. I think it's an interesting implication that Yumi, whose whole life is defined by her role their society, is not special. We know that the nightmare painter is nor a power, just a skill. While this doesn't have many more implications beyond that, its interesting nothless.
(I reposted it since I realized the title was a kinda spoiler)