He went off to sell Amrita soda in the void after being banned from coolest night club around.

He still exists within the later games, usually in the form of a blue butterfly.

The blue butterfly thing is mostly speculation. There's never been actual confirmation that, that is Philemon. In previous entries Philemon was always a golden butterfly so it seems somewhat overly optimistic to me to assume he's the blue butterfly later on. It is possible though.

It has been confirmed in an interview that the blue butterfly in Persona 3 and 4 is Philemon. The one in Persona 5 kind of muddles the water a bit though.

Why must there be so many gods in the Persona series?

Persona is a spin-off of smt and having many gods from different cultures and mythologies is kinda a big part of smt.

I'll go investigate this right away.

He went off to sell Amrita soda in the void after being banned from coolest night club around. O H