Btw corporatism can in theory exist in a decentralised state, as well in a very centralised one ( fascist italy). Philosophically fascism and extreme socialism only have one thing in common, disdain for bourgeois principles like individual liberty etc. but thats it.

Italian facism was corporatist, not socialist. Mussolini was indeed influenced by the revolutionary syndicalist, Georges Sorel, but mostly by his apologism of political violence break the control of the bourgeoisie, via worker syndicates running the economy by themselves in a decentralised state. Corporatism is when worker syndicates and employer organisations merge into a single trade corporation for example, agriculture. The state mediates between all the different corporations, when they present their collective demands, and regulates production. But corporatism is hierarchical and authoritarian, its not the socialist dream of a classless society. And lastly, corporatism naturally doesnt eist in the usa, state monopolised capitalism does.