"your do_stuff( ) example would be in a "Monolithic style",
Not really, because in do_stuff, you have many many private methods. (If only people writing BADI implementations would realise this!) The point I was trying to make is that you can write procedurally just using a single method and an instantiation. I.e. instead of forms, you can use methods, which are better for all the reasons you describe. So even not using what SAP define as obsolete, you can stick to procedural programming if you think that's better.
As far as Mr Krubner is concerned, I don't find many software specialists have cited him as an authority.
I have found (in my nearly 20 years of ABAP programming) that OO programming when done well, leads to more easily maintainable and more robust programs than well written procedural programs. (Since I am comparing like with like, I'm not committing the Scotsman fallacy. As a corollary, you may take that I consider all badly written programs to have equal value). I've also found that objects lends itself more easily to abstraction since you can pass around the entire context of the abstract representation. Overall, I find that OO development decreases the total cost of ownership.
However, regardless of the programming paradigm, if you do not have good programmers, all bets are off.