I stopped reading at "agile software development." Agile serves as no justification for anything except endless meetings.
You initial point about small vs. large objects in complete bullshit.
If you are getting mired in spaghetti gloop writing OOP it can only be because you are not doing design before coding, and the reverence for agile corroborates that. These methodology fads deprecate design to promote haste; OOP requires design.
I'm guessing you're a relatively junior programmer (I'm in my 33rd year of development) and you think design specs are obsolete. Small wondeer you paint yourself into corners,.
In 1995 I took on a project at Intel that should have been way over my head. But I broke it down into components—objects—and did six weeks of coding without a single test and at the end everything worked.
I planned my work.
It could not be clearer that you don’t really know much about object oriented programming; you buy into that agile crap so you probably think that upfront design is obsolete, you plunged into some project in a barely-learned object-oriented lanuage, quickly lost control of your code and decided to blame the approach instead of your lack of planning.
Well, OOP is very design-centric. There is a lot more to it than a this-pointer, decomposing your work into meaningful objects and defining their interfaces is what it’s all about. It is not amenable to the haste-driven agile approach.