Dressler et al. (2019, https://www.italian-journal-linguistics.com/app/uploads/2021/05/3_Dressler.pdf) report several cases of rather unusual patterns in children’s morphological acquisition and suggest that these patterns pose challenges to both usage-based and universalist theories of language acquisition. We argue that a learning-theoretic account of how such patterns might emerge is missing from current theories, and show that the Tolerance Principle (Yang, 2016) provides such an account. We apply the Tolerance Principle to both types of "blind-alley developments" discussed by Dressler et al. and show that it successfully accounts for these patterns as transient mismatches between form and function during acquisition.