Tim Witt wrote:

Another possible reason for requiring the ADF or Radar is the fact
that the min safe altitude is defined off the compass locator. An ADF
(along with your compass/DG) would allow you to determine if you were
north or south of the locator. The localizer and marker would only
tell you when you were at the fix.

No way. The MSAs are not part of the regulatory or operational scheme for
IAPs in the United States.