> If I understand it right, in a simple case like this: 
 ...
> calling super is equivalent to calling object.__setattr__,

It is not equivalent.  Instances of Foo() would behave equivalently but it might do something different for subclasses of Foo.  If you're interested in learning more about super(), have a look at:  http://rhettinger.wordpress.com/2011/05/26/super-considered-super/

In the meantime, I'm closing this because we do not make that blanket advice to always use super() instead of a direct call to a parent.  Sometimes you want one and sometimes you want the other depending on what you're trying to do.