Noting that tsuwm's final paragraph makes the point that circumstances alter cases:

Max, can you and I temper our disagreement by agreeing that in some specific cases the plagiarized author will be, and in other specific cases will not be, the primary victim of the plagiarism? That not every case will be as I suggest, and not every case will be as you suggest? In short, that each of us has overgeneralized?

(and that a particular case might of course be arguable and might depend on the definition of "primary")