What do you mean, "run your own resolver"? That's a fancy name for the library that the application uses to speak DNS, not a separate thing that has to be set up, run, etc, separately.
Instead of asking "what IP is Google.com?" to your configured DNS server, you traverse the whole chain. First, you refer to your list of root zones: which servers can answer about .com? Ok, ask them which DNS servers google.com should have. Next, send the request directly to those servers. Now you get a response that you can use.
This chain can get really long depending on the service's DNS configuration. And this whole time every request has to come back DNSSEC signed.
