Speaking of moral tribes, Walter Laquer:
False optimism, then, can explain the Deutscher-Carr syndrome only in part, and their enduring reputation in some circles not at all. Similarly unhelpful are explanations that appeal to the perfectly natural reluctance of authors to admit mistakes—another hardwired tendency. In the end, the most crucial factor may be just this: being in tune with the right crowd.
As the leftist French journalist Jean Daniel once put it: better to be wrong with Jean-Paul Sartre than right with Raymond Aron. Sartre might have been consistently wrong in his political judgment and his intellectual opponent Aron almost always right. But Sartre, like Deutscher, was pro-Soviet during the cold war while Aron, like Isaiah Berlin, was pro-American (and also, like Berlin, pro-Israel). And that settled the matter.
This is how reputations quite often develop in the world of ideas, and how they endure—an interesting issue itself, and certainly one in need of further investigation.