Yes, this. Nobody came along and decreed the dictionary was descriptive - which would itself be a prescriptivist view of the world - it just is.

Linguistics rejected prescriptivism because it is a failed model of reality. I think the reason so many people cling to a prescriptive model is because in school we were taught obedience above all else, which is a terrible way of educating people, but maybe it helps to maintain a subservient class of workers.