Living in a universe where your fetish dominates the whole world would be fun but very inconvenient. Into vore? Your girlfriend is a pred who eats you. Feet & farts? World smells like ass. Weight gain? Noone works due to being housebound blobs. Inflation? Random growth. Giantess? Whole city crushed.

BDSM? Yeah the whole world is a red light district where you getting tortured is your masturbation. Transformation? Good luck every five seconds you'll transform into an elephant or a bimbo. Diapers? Have fun needing someone to change you all of the time.