What exactly is the use for Edit Mode/W/ Subdivide (Smooth)?

I would expect the tool to apply a catclark operation on selected faces of a mesh.
This is the result I would expect from it: https://imgur.com/a/bdWEK2n

This is what the tool gives: https://imgur.com/a/MkuDgid

The result looks different from running a catclark.
It has been like that for as long a I remember but why is it like this?
And what is the use case for the tool with the current behaviour?