You can have free functions that operate on your classes instead of shoehorning every operation into one class or another or creating new ones from whole cloth just to hold a function (e.g. the Hit class mentioned earlier).

Writing methods makes it easy to add new types but not methods; you have to change every class to implement a new method. Writing functions makes it easy to add new function, but you have to update every function for a new type.

Each has its place, and issues arise when certain languages (e.g. Java) or paradigms ("classical" OOP) make it impossible to use one or the other style.