Oooooh, materialist, I read your post and got all excited. 
Yes to what you said. A big fat yes.
Crikey, I have to try and organise my thoughts now .... the problem with postmodernism is that you can't map power onto it because it is the recognition of the multiplicity of individual perceptions.
What I think happened was that, in the pursuit of power within the postmodern context, the individual then expanded to become "class" in a kind of "I feel, therefore I am legion."
An example ... you have an individual. Lets call him Bob. Postmodernism validates Bob's interior world and perceptions. Okay. The problem comes when Bob wants power over others. How can he achieve that? He's one ontology competing with millions of others.
It's simple. He borrows from Marxism. He multiplies himself through reflections, and then puts forward those reflections as evidence of a "class". Those reflections are all Bob, but few people realise that. All they see is the power of a multitude, the power of class, and this class using Marxist concepts to push forward their class claims.
Essentially, Bob takes postmodernism, hitches it onto the cart of Marxism and then drives that waggon all the way to the centre of State governance and policy.
Hence the confusion about what the waggon is: postmodernism or marxism? Well, it's both and neither. It's Derrida's zombie: neither one thing or another but both, which I suppose bollocks means the phenomenon is fundamentally postmodernist in form. Bugger.
Any how, I think you can see Bob's process very clearly with TRAs and their activism. They project this notion of a legion, of a class, which is very easy to do when you have millions of mirrors and thousands of strands of communication, which the internet provides. The reality is that this legion doesn't exist; it's a mirage. And it has no realistic or viable claim to interfere and change policies that affect millions of people.
However, the crook in the tail is that the very act of projection recruits. If Bob reflects himself enough to create false evidence of a class, sooner or later, other people will come along and look at that projection and identify with it. "Oooh, look at all these Bobs. So many people must be a Bob. Am I a Bob? Yes, I think I am." So the mirage becomes material.