The strongest argument against the black ops theory, it seems to me, is that such an accomplishment is beyond the imagination and the competence of the politicians in power.

Did they want to go to war with Afghanistan and Iraq?
Did they want to make billions of dollars for their corporate friends?
Did they want to "transform" America's military?
Did they want to increase Executive power?
Did they want to expand America's power?

Yes.

Did they manage to do all five?

Yes.

How then can anyone argue that they are too incompetent?

Then, let's take a look at how competent they were at selling the wars. Then, let's take a look at how competent they are at stealing elections. Then, let's take a look at how competent they were at obstructing justice. And on, and on, and on...

Let's also not forget that their imagination was good enough to know that they would need a "New Pearl Harbor" in order to accomplish their goals.