It was part of his promise he had with Nyrp.
The recreation of the world was to allow them to reset things, and let humanity run it's own course without those to having direct influence like they did during P2.

To show up would to be violate the entire reason the world was reset.

Yeah. That is kinda my fault.

Ah. Well, that cleared it up. I must have forgotten something from P2.... But I wonder ehat happened to the other Residents of the Velvet room too. My memory seemes to be failing me on the subject.

I think Igor decided to kick them all out and start building his harem once Philemon wasn't there to stop him. Kinda sad, since I really loved all of them.

I dont know. But the Harem idea made me chuckle. Nonetheless, the other residents had quite a bit of character. They were very unique and had purposes for the room... If my memory serves me well, that is.

Yeah. I feel part of it is because most of the residents in P1 and P2 are actually humans that came to the velvet room for their own reason IIRC. Meanwhile I'm pretty sure the attendants from 3 and onward are beings made by Igor and therefor don't really have a reason to be there besides that they were literally made for it.

That does make quite a bit of sense. I would like to hear more opinions on this.

I feel as though that the Demon Painter may still exist in some capacity.

Well he was modeled after Kazuma Kaneko, sure he certainly does live on in that aspect. In the games though, it is possible although I'm not sure if he really does or not.

Philemon isn't the butterfly in P5 though. No spoilers.