Is the best-case scenario that, since the force is being transferred to both wheels, you might not peel out as often when you start to ride? Well, THAT certainly justifies the extra weight, expense, and whatever portion of power is lost in the transfer!
Snow, ice or sand is the only terrain where this design would make sense. And in flat, soft and squishy terrain like sand or snow it makes a lot of sense actually. Just like cars.
But just like cars, very few vehicles need to be front and rear wheel drive.
That fat bike looks like a lot of fun, you could ride over almost anything. I'm surprised people here are poo-pooing these. I doubt I could ever justify spending however many thousand these would cost but I'd love to take one out on the trail in the snow.