For a given repository, we have two ways of setting minimum number of reviewer approvals to get a pull request into a mergable state. In the Default Reviewers settings page one can enter the number of Approvals Required. In the documentation for this you state: In the Approvals required field, select how many reviewers must approve pull requests that match this criteria before merging.
This does not appear to do anything. To get an actual barrier between pull requests and merges, one must set Requires Approvers field in the Pull Request setting page.
Seems to me these two fields should be linked. If I set the Approvals Required field in the Default Reviewers settings page, that setting should be forwarded to Requires Approvers field in the Pull Request setting page.