This is really unfair. It is a consequence of their principled scrupulousness that S&B insist that they are not experts on the sociological and cultural issues raised the works they address. They restrict their critique to the misunderstanding and misapplication of scientific theories within the works of these writers.
Compared to the cavalier and often moronic abuse of scientific ideas that they expose, S&B's careful insistence on the limits of their own expertise is not a disadvantage. On the contrary, it is an example that those they criticise ought to have observed.
Clearly in the humanities it is considered good practice to rant on about things that you do not understand, otherwise it would not seem quite so odd that someone should willingly choose to be honest about the limitations of their expertise.
-- Jim heartfield