Mark Fisher, and the 'traditional left's' critique of neoliberal identity politics calls for a centering of class -- that is the power relations inherent in capital modes of production. This, many would argue is not an identity, but a _material position_: a specific stance or relationship to the productive forces in society.
The Alt-Right tends to believe societal conflicts arise from 'culture wars' between ethnicities, nationalities, religions, etcetera. In this way, they share an 'identitarian' analysis of political force with the liberals they aim to critique!