Except that your queries are spread out to different places instead of all being sent to a single server.
You ask .com resolver for domain.com's NS, and then you ask ns1.domain.com for foo.domain.com. Then you browse to wikipedia.org, and none of those DNS queries go to the same place as the previous site.
You ask .com resolver for domain.com's NS, and then you ask ns1.domain.com for foo.domain.com. Then you browse to wikipedia.org, and none of those DNS queries go to the same place as the previous site.