Most people in the outgroup who know about the Sokal Affair but who know nothing about the journal they submitted to aren't aware of this, but Social Text was known to be not peer reviewed at the time. It's not that reviewers failed some test; there explicitly and publicly wasn't a review process. Everyone reading Social Text at the time would have known that and interpreted contents accordingly, so Sokal didn't demonstrate anything of value and was just being a jackass.