The physiological aspects are not merely “partly” the problem. They’re the most significant portion of the problem. You can of course argue that certain other factors lead to chemical dependency, but “addiction” itself is specifically referring to the chemical dependency.

When someone is actually, clinically addicted, it means that their body has to have the substance. Not getting the substance can make them terribly ill. Even killing them in some cases. It works the same with alcoholism. Alcoholism isn’t a code word for “Susan drinks too much at Christmas”. Alcoholism is a specific condition that refers to chemical dependence on alcohol.