A reviewer is not there to learn. If anything, they're there to teach. What good is a reviewer that can't grade others on their adherence to the coding style and application architecture of the project? They're supposed to determine what goes in or not.
This discussion is about newcomers that know basically nothing of the project. When I say they're not there to learn, I mean their primary function as reviewers isn't to learn from what gets submitted. They can learn depending on what gets submitted, but if 90% of the time their ignorance doesn't permit them to properly determine if what's submitted to them is good or not, then what's the point of their review?