[cestith]

You do make some solid points. You assume, however, that there's a bandwidth cost between the load balancer and the backend which won't be true for everyone. You also don't consider the cache behind the load balancer might be much larger and have a much longer TTL than the CDN's cache. Economics of this sort of setup are entirely different if you're putting every piece on a cloud instance rather than having a rack somewhere with your private data flowing for free over your own switch.