If I'm not mistaking, Marxists see Corporatism as "decadent capitalism," where the business class influences and controls government activity to the horrid disadvantage of the common worker. Although, we must note that almost every liberal, conservative and socialist equates corporatism with "business first, government second," which is a gross factual error. Corporatism, when it was practiced by the Catholic Church and Fascist Italy, employed the opposite of what these groups might call it: government coerced corporations into accepting state commands, absorbing them into the state apparatus, while retaining private ownership of said corporations.
The basis of anti-corporatist thought is an error, however. When the groups I've mentioned above talk about corporatism, they seem to automatically refer to "corporations," or "business corporations," when, in fact, "corporatism" stems its structure from
corpus, the Latin word for "body," and doesn't implicitly require extension into the business environment.
Even Penguins are corporatist, in that they commune within strong familial groups and form a so-called "body" in relation to neighboring groups.
(Penguins are fascist.
)