Sounds like someone doesn't know what plot is. While P3/4's plot are both thin, the elements surrounding it: characters, theme, symbolism are all great, making it a great story.
That said, P4's s links are way worse than P3's. In P3, you play as a crafty devil who dons multiple personas to make people do your bidding. Convince a little girl to run away? Easy! Make your homeroom teacher fall in love with you? No problem! Convince your fellow student to keep going to kendo practice despite risking not being able to play sports ever again due to a leg injury? Where do I sign?! Raid bathroom stalls and bully students to find a perp who did drugs on campus?! Fuck yes!!!
P4's are more boring in comparison, and this is without mentioning the wonderful Sun slink in P3 where you help a dying young man come to terms with his life coming to an end.