Reviewers and Participants are not subsets of each other - you can be a reviewer and never participate and you can be a participant but not a reviewer.
Reviewers who don't participate can be a problem because you were not just put there to be notified, you were given authority to stamp it as ok or not. So, participation is probably expected.
A high number of non-participating reviewers could be an indication of a poor review.
Reviewers and Participants are not subsets of each other - you can be a reviewer and never participate and you can be a participant but not a reviewer.
Reviewers who don't participate can be a problem because you were not just put there to be notified, you were given authority to stamp it as ok or not. So, participation is probably expected.
A high number of non-participating reviewers could be an indication of a poor review.
So, let's make this a method for CodeReview.