Yes - selectively picking the ones which say three, but excluding those which say two; that's the point I was hinting at.
Of course, few analogies do hold true under all permutations, but my point (again) was that saying a shape has to have at least 3 sides to be two-dimensional may be true, but is as relevant to music as the theory of dinosaurs which states that they are very thin at one end, very fat in the middle, and very thin at the other end.