It may be an imperfect analogy, but to call it "rude" seems like a stretch.
Most arguments can be made so that the 'opponent' is receptive and thankful for your input. The arguments which cannot, are perhaps best left unsaid.
I've offended plenty of people, and I can't recall ever winning an argument against them afterwards - at that point, things like facts and customer benefits are irrelevant, and it simply becomes about not letting the other person "win".
I didn't say it was easy, but since when were humans easy?