Not so much P3, but definitely for P2, since Philemon and Nyarlathotep are both fairly important in both games.

Understood but basically four and five it has no meaning?

Well it's not super important to 3 but there are many plot points in 1 that have influence in 3

Eh, from me small experience in 2 it doesn't really seem necessary, and 3 it might just be the subtle separation of the Nanjo group and Kirijo