My main problem with OOP is that objects don't bound complexity.

If I call a function with some arguments, that function is composed of smaller functions which can only ever operate on the arguments I passed the parent function. As I follow the function down to primitives, each piece of code is operating on less data.

If I call a method, that method can operate on its arguments, properties of the object, and properties of the superclass. I often find myself ping-ponging around the code base as a class' method relies on a method of an abstract superclass which itself relies on methods of the original class, each step introducing more properties into the calculation, many of which are objects themselves!