Back then, constructing decorators using function closures had various short comings and the resulting wrappers didn't preserve introspection and various other attributes associated with the wrapped function. Many of these issues have been resolved in updates to Python and the functools.wraps helper function, but wrapt based decorators were still useful for certain use cases such as being able to create a decorator where you could work out whether it was applied to a function, instance method, class method or even a class.