It's reasonable to criticize people that take the ideas and concepts from postmodernism too far into nonsensical corners.

But postmodernism, as a philosophical and larger historical/analytical approach, is not some evil boogieman. Lots of things have been done based on purported science knowledge that was, with historical context and with a proper critical eye, complete nonsense at best, and evil at worst. It was quite easy to make phrenology look like science. Postmodernism studies how it is possible to make something look like science. It's a complicated topic with consequences for the framing and development of scientific knowledge. There's no reason to discredit scientific endeavor in totality because of that though, and, to be honest, those people are far more fringe in academia, for instance, than people realize. And just as well, properly framed, there is no reason to wholesale discredit the critiques made by postmodernism of the uses and abuses of scientific knowledge by scientific institutions, governments, individuals, and the ways that arose out of culture and historical context.