French (?) philosophy

In the SD
I read the Rabbi's fascinating and successful column on the state of philosophy today and on the French in particular. I personally tried to read Levinas' book "Totalities and Infinity," which sounds quite explosive and profound, but I couldn't really understand what he was saying. On the other hand, one of the well-known French thinkers is Michel Foucault, who is considered a guru in the postmodern world and is usually associated with a school called "structuralism," which is currently considered an important current in philosophy, social sciences, anthropology, and even linguistics (speaking of Noam Chomsky, who is also usually associated with this school; see the book "Structuralism" by Jean Piaget, who is also French). Is the Rabbi's criticism also directed at these people and why? Also, how does the Rabbi explain the enormous influence of a philosopher like Derrida on human thinking and on issues like moral relativism, etc., despite the fact that according to Rabbi Gottfried Empty of content?
Thank you very much.