Both issues are entirely valid, but not unique to white balance. Attempts to use a grey card for exposure can fail for the same reasons. This does not mean there is anything wrong with either use of a grey card, only that no one technique will work in every situation.
As for white balance, you as photographer get to decide how best to do it. Nikon provides a selection of "standard" settings, and you can set your own as discussed in this thread. Any neutral area sufficiently large in the light where your subject is will work, be that grey card, snow, rocks, a white wall indoors, or whatever. If your subject is some distance away, it makes no difference if you zoom in with a telephoto to do so, or if you walk over to the subject with the camera.