No claim, no matter how absurd, is immune from belief by someone or some group. History exists only in the minds of historians. The past is constructed by historians, much as sculptors construct figures out of marble. Historians can no more purge themselves of bias than anyone else, including physicists and biologists. There is no complete causal structure of contingent events in the past.
Historians construct a causal structure in their minds out of the available documentation.
Historians' job is to present this constructed past not as it actually happened but as it might have happened in one interpretation only. The relativism of the 1920s, 1930s, and early 1940s returned in a different covering cloth as literary criticism and deconstruction in the late 1960s, 1970s, and 1980s. Just rewrite the past to fit present needs. History empowers, so it is acceptable to deconstruct the history of those in power, and reconstruct it for those who are not. Native-Americans are also recapturing their past, but in the process some are blaming the white European male for all that is evil in the world.