This is an affliction by which people muddle objectivity with neutrality. One can adopt a neutral (NPOV as they say in Wikipedia land) vantage point, yet be terribly biased, even if it is simply confined to what is filtered out. One can be biased to an intellectual (or political) plank, yet be objective in evaluating arguments and evidence.

Yes, tribalism can induce such ills as well as invoke cognitive dissonance, but it is not a default setting.