I don't claim to be a Foucault scholar but I've heard that claim. The postmodernists were, and to some extent I can sympathize, hostile to grand narratives. Especially given the end of religion and in the middle of the Cold War, who can blame them. Even the attack on Western Enlightenment ideals is at least interesting to discuss

But as you say the whole thing is a giant metanarrative times ten, and these language police types are running over everyone who gets in their way. It's making so many people nervous, I think it has a shelf life. What scares me more is the open embrace of postmodern social theory by corporate America. That will lead to a backlash that makes me even more nervous.