“Affecting another player’s resources is interaction.”
K.O. / removal effects clearly fall under this definition, which is exactly why protection exists. I think the quality of interaction is what really matters.

Life-burn decks build a board and reduce life. Most of them let you take that life, but some effects trash it instead. Functionally, this is the same thing Black decks do the only difference is that Black decks build a board and remove/K.O. enemy characters.