I get where this poster is going with the idea of using different resolvers for different services, but there's some serious flaws in the logic. 1) Many sites utilize a redirect in order to force the user back into the optimal datacenter. Using anycast name resolution the user will always end up in the closest datacenter. This is a pretty standard CDN offering by the first tier providers. This is utilized mostly because using a DNS provider like Google would otherwise result in traffic flowing to datacenters thousands of miles from your home. It's also used to to ensure geo restrictions, which would kill this method for many sites. 2) The poster mentions setting domains like Netflix back to the original DNS server. Content delivery is a bit trickier than this. Fire up Wireshark when you're watching Netflix and you'll see there's a large number of domains involved, and the actual content comes off a third party CDNs. Setting DNS servers per site is a lot more complex than choosing a single domain name and setting it to a server.
-Ex CDN worker