This commentary discusses the recent keynote article by Westergaard (2021), which is an interesting contribution to the field of language acquisition and multilingualism, especially because it attempts to provide a wider perspective by embracing first, second and third language acquisition. I address major claims put forward by Westergaard, to support them with my own research data from the domain of phonology as well as to raise some questions as to potential limitations of the approach, and to point to avenues for future theoretical and methodological refinement.