Disagreeing with everything someone says doesn't stop them. It let's them set the agenda. It is the way trolls work to feed the fire of their destructive aims. Contrary is not Contrarian. Contrary is coal for hell fire. Playing devil's advocate, or always critiquing, doesn't build up the power that feedback from a trusted partner brings. If you give someone a Bull Quota, putting to side points of disagreement, and try to understand the thread of their argument, it can allow you to see their actual point. Nothing exists without context, and if the context isn't first understood then disagreement is just bluster. Don't feed the trolls.