Both the sokal paper and the first paper by the Boghossian group were published in open-access journals, of the same standard as the other fields. The only papers to be published in peer-reviewed journals are the last few by the Boghossian group, and those don't really prove that it's a problem unique to social sciences, either. The Boghossian group didn't seek to establish a control study, so we don't know if a similarly motivated group couldn't get papers published in other fields.