Harman’s OOO is split into an esoteric and an exoteric version. The esoteric version is the arid, abstract, de-qualified and de-quantified void, where no examples can be given, and the concepts are empty meta-concepts awaiting yet forbidding instantiation. The outer face of OOO is one or another (forbidden) instantiation, providing examples that can appeal to various audiences or targeted publics. This is why Harman never replies to criticisms but just repeats the basic principles and moves on to a new venue to propose yet another iteration of the system, counting on the intuitive appeal of that iteration to produce a shock of recognition.
I think with Deleuze that philosophy (Deleuze’s “concepts”) is tied to non-philosophy (affects and percepts) in specific modes of subjectivation that get disciplined by all sorts of structures, codes and stereotypes. OOO, with its dichotomy between real objects and sensual shams, puts obstacles in the way of such an interaction, and tends towards what Badiou has dennounced as “democratic materialism”: a de-conceptualised subjectivation for the people, and a debased functional conceptuality for its managers.