[kazinator]

Less, I would say; because using OOP for everything is straightforward, just obtuse, verbose and possibly slow.

You don't have to solve paper-worthy academic puzzles to use OOP everywhere.

Using OOP everywhere has been done and probably continues to in some shops. There was a time in the 1990's when nobody was fired for using OOP everywhere.

In Common Lisp, absolutely every value you can create has a class: the class-of function is meaningful for any value. You can replace all the defun forms in a Common Lisp program with defgeneric and defmethod.