I think you can imagine everyone has ankle weights on, or technology, and there's a reason that people aren't floating around. But I also liked this idea that in this world, people forgot they can swim. The modern world weighs you down, there's always emails to check, you've gotta go to your job and pay your mortgage. You're not really thinking, "Oh, yeah, I can swim around." BoJack discovering it is a big deal, and kind of fun.