DOF and subject isolation (or background blur - or do you mean something else?) are not necessarily the same.
A lot of people seem to have difficulty grasping this concept. Including some who think they know better in this thread. Its shown quite well in this article.
Note that no where in the luminous landscape article did the guy refer to subject isolation.
Taking pictures with a short focal length and short subject distance vs with a long focal length and longer subject distance (for the same framing, using the same camera and aperture) results in the same dof, but the latter will give you a much blurrier background.
How about - "For the same magnification of the area in focus (different lenses, different distances), longer focal length at the same aperture will give you same DoF and more background magnification".