what should mountd do for NFSv4 only servers?

[Rick Macklem]

I recall an email discussion with Jason Mader w.r.t. what the behaviour of
mountd(8) should be when an NFSv4 only server is being run.
(I seem to have misplaced the email, so if I recall incorrectly, I apologize and hope
 that Jason will correct me.;-)

mountd(8) serves the Mount protocol, which is related to NFSv2 and NFSv3, but has
nothing to do with NFSv4.
- At first glance, that would suggest that mountd(8) shouldn't serve Mount protocol
  RPCs at all for a NFSv4 only server.
  However, this would imply that "showmount -e" would not work.
  I recall that Jason felt that "showmount -e" is useful, at least when run locally on
  the server.

As such, how does having mountd(8) service Mount protocol requests only from localhost
(127.0.0.1 and ::1) and only handle the Export RPC, when the NFS server is configured
as NFSv4 only via vfs.nfsd.server_min_nfsvers == 4?

Any comments, concerns or other ideas please, rick