It is not an extremist position. Everything is experienced through the medium of thought which makes all experiences highly subjective.
To magnify, the world as experienced by a single-cell organism is vastly different from the world you or I experience.
No doubt there is "something", but it is the height of human arrogance to believe that our version of that "something" is the correct one.
What scares me about postmodernism is that many of its adherents seem to reject the idea of objective truth completely. That way madness lies.