I understand the need for fat bikes on snow or sand dunes, so what's with all the fat bikes people are riding in sunny unsandy CA?

Am I missing some hidden benefit to them like ultra smooth ride?

I keep on thinking Forrest Gump would ride a fat bike (because they look a little ridiculous). It takes all my self will not to yell, "Ride Forrest, Ride" when I see someone on my MUP ride one!