Hmmm. I wouldn't define a great "team" as dysfunctional. Some might point to "high-performing" teams and say something like "well, their results are good even if the tensions are high." To that, I would respond, what would happen if you lowered the tensions? Might performance be better?

Also, on another note, what constitutes "conflict" varies from team to team. What looks like heated debate to some might feel like healthy discussion to another. It is relative to people's perceptions.