Allport defined stereotypes as inherently inaccurate partly to side with activists.

Evidence

Because activists rail against the stereotypes that have characterized their groups on the basis of their traditional social position, theorists such as Allport have overaccommodated by defining stereotypes as necessarily inaccurate. — John F. Dovidio, Peter Glick, Laurie A. Rudman, On the Nature of Prejudice, 217

Categorization

• corroborated: 2 independent passages support this claim — John F. Dovidio, Peter Glick, Laurie A. Rudman, On the Nature of Prejudice: Fifty Years…, 217