Inheritance is not important, but the organisation of data. What if you have a GUI with say a tree view element, a list view element, and a text element. How would you create that in an non-OO way? I suppose you could write

var tableData = ... var listData = ... var textData = ...

and then add callback methods (all in the same source file?). But that runs out of hand real quick. It seems much nicer and cleaner to have a treeView object that knows it's own data and callback methods.

What if you have nested elements, like a window with those three elements, or something else. How would you hand that data around?

I have seen the make-struct macro of MzScheme, but once you start using inheritance with that, it starts getting really ugly, imo.