I'm not sure on the actual design decision reasonings, however you can reach many of the exit junctions with multiple routes. So if everyone drove around it sensibly, there _would_ be fewer cars stuck in traffic.
I'd have to see a study or simulation. I can't take it on faith, because what I see is very many points where cars have to stop and yield. Multiple routes could just imply packing more cars into one ginormous intersection where they block each other trying to get in or out. And where you have multiple routes to one junction, you have merging.
