Maybe it lingered from earlier drafts. IIRC,
Tolkien originally had the
Istari and
Nazgûl as
Numenorean. That might make them more magical.
But maybe there’s more to it than even that. Remember the Stone of Erech. And the Oath taken there and the Curse laid on the oath-breakers by
Isildur. And the construction of
Orthanc and
Angrenost.
Amon Hen, and Amon Lhaw, and the abilities they granted to see and hear.
Aragorn’s strength of Will, and ability to wrest the
Palantir from
Sauron’s control. The flashes of insight by Aragorn, his grandmother Ivorwen, and so many others. His ability to call the dead oath-breakers…
There’s probably more.
Maybe we underestimate the special abilities of the
Dunedain, and fail to understand what they really are. Maybe it’s even part of the special blessings given them when
Numenor was founded - most evident in height and lifespan, as well as foresight, good health, and “good luck” or special protection in their sailing ventures. Maybe there’s more to it than just that.