Every critical theory considers Marxism, because the methods Marx proposes of critiquing given structures can be useful in other critiques: once on identifies a method of approach, entire critiques become possible. Class, race, capital, and all sorts of other possibilities.

Adam Smith's critique of feudalism (including mercantilist evolutions of feudalism) is pretty fundamental to capitalism. Most people quote Smith without reading Smith - and misunderstand what he wrote and why. A critic, and critical theory, builds up from Smith through Ricardo beyond Keynes and Marx and Friedman - assembling the same sorts of fundamental challenges to dogmatic slumber that Marx offered, but using whatever bases seem most interesting for critique.

Without such structures and the ongoing processes of critique (including some innovations that come out of various critical theories), liberalism would be impossible. With such critiques, liberalism can be healthy - because it is capable of responding to pseudo-Marxists and to commercialized dogmatists.

It is strange to think critical theory is harmful to anything other than dogmatic assertion. Can you identify a concrete harm?