Theory vs. knowledge

"Grad students in the humanities, who ought to be studying [history and literature], instead spend a lot of time reading 20th-century theorists whose long-term relevance is doubtful at best. The amount of reading time spent on theory rather than primary source texts is just way out of proportion to any possible use or importance that the theorists might have. Trotsky? Important. Foucault? Important to the academy. There's a difference. Isn't there a whiff of self-esteem-ism in declaring — to academics — the enduring importance of academics?"