Ayn Rand is regarded as the philosopher of reason and individualism but her Objectivist followers display a tribalistic behavior. In his book The Contested Legacy of Ayn Rand, David Kelley talks about the tribal element within the Objectivist community. Here's an excerpt:
Within the Objectivist movement, a tribal element has long been at war with a rational one. The rational element is a real and important side of the movement. Objectivism has been a positive and liberating influence for many people. It has set them free to develop their talents, realize their dreams, achieve their happiness. But I think it’s clear to any objective observer that there is a tribal element as well.
Objectivism is a philosophy of benevolence. It sees the world as an open sunlit field, where success is the norm, where we can approach others with the expectation that they will be rational. And many Objectivists have this attitude. But there’s also a darker streak in the movement. Many Objectivists seem shut off from the world, profoundly alienated, seeking friends only among other Objectivists, regarding outsiders with suspicion. They speak freely of the enemies of Objectivism, often with a paranoid sense that the world is scheming to destroy us. They suspect that anyone who succeeds outside the movement must have sold his soul, as in Peikoff’s dark allusion to those who “have one foot . . . in the Objectivist world and the rest of themselves planted firmly in the conventional world.” Objectivist publications have been largely negative in content, filled with horror-file items rather than positive contributions to knowledge. Objectivists sometimes seem to take perverse pleasure in contemplating the awfulness of their enemies. And some have acquired a zest for moral condemnation, an act that benevolent people experience as the occasion for sadness and disappointment.
Again, Objectivism is a philosophy of independence, but within the movement there has always been a certain pressure for conformity in thought and action. When people join an ideological group out of an antecedent and independent belief in its ideas, one expects to find agreement in basic outlook. One does not expect the degree of uniformity—down to matters of personal dress and style, aesthetic preferences, beliefs about political strategy or sexual psychology—that characterized the Objectivist movement, especially in its earlier days. Such conformity was produced in part by a fear of moral condemnation for deviant attitudes or values, a fear that was not without foundation. And in part it was produced by a willingness to substitute authority for independent judgment. In my experience it was not uncommon, especially during the various purges and schisms, to hear explicit appeals to authority: “If Ayn Rand says that so-and-so is a rotter, then he must be; could the author of Atlas Shrugged be wrong about it?”