Is there any advantage to using generic collections when you are only storing reference types?

Question

I have been reading a book and encountered a statement, that generics allow the programmer to avoid need of boxing and unboxing when using e.g. Stack.

I think it is not entirely correct as the Stack (not generic) could hold just reference type variables and then there is just casting, no boxing.

EDIT: AFAIK, boxing relates to only value types to object conversion. Is that correct or am I missing something?