The problem is that words are fuzzy. They change meaning based on how people use them. Dictionaries are a trailing indicator of how people have used them in the recent past.
There are two things that call themselves “feminism”.
One is about making women strong, getting women to do more. That is good, as making people more capable is a good thing.
The analogy to dermatology is pretty weak. Calling yourself a dermatologists requires a certificate. It is a term that is owned by an organization that protects the brand.
Feminism does not have that kind of defense. Anybody can call themselves a feminist,