I do agree the "noun" vs "verb" analogy when classes are taught are horrible..actually the way classes are taught in general are just confusing.

Ultimately, classes are about code organization and reuse. Done properly, it leads to a well maintained program. Functional programming...it still needs to be organized somehow, whether you put them in classes or namespaces, the last thing you want is spaghetti code. Now depending in the type of programming, you may need to preserve state, which can be quite challenging in a purely functional environment.