It's also remarkable in Atlus' case because they had to go through a bunch of stuff like developing their own engine, Index blowing up, the Sega acquisition, Persona 4: Dancing All Night's original developers being put aside, etc. Hashino's mentioned in recent interviews that there were times when the team was uncertain and that it got to the point where they were scared P5 might never even come out, but it all worked out, in the end.
it is kinda crazy that it has been about 8 years since the last mainline entry. This probably should be getting the same reception as games like last guardian and ffxv but the multiple re releases and spin offs probably helped avoid that perception and also it probably helped they didn't announce the game officially a long time ago.