Well, Erik's looking at early Fascism. This was a program drawn up by, sure, a bunch of Arditi, but those guys were outnumbered at the Milan meeting by students, syndicalists, and even Futurists. They were the ones who started the original Fasci di Combattimento as the third way opposing Socialists (who were unpopular for having to admit the failures of the war) and the Popolari (who were unpopular because lol reactionary papacy).
Within eight months the whole idea of a third way caught on so quick that the November 1919 elections had sixteen different 'Fascist' parties putting up candidates with platforms like Mussolini's and d'Annunzio's, which had little to do with the original manifesto. And the failure of the Fascist parties in 1919 meant that the ones who survived would determine what the term meant from then on out; enter the ras local "big man" leaders like Farinacci and Balbo, who took advantage of popular fear of the proposed expanded Socialist platform and ongoing strikes to remake the movement in their own image, and to a lesser extent the image of Mussolini. And then later Mussolini got to mold Fascism into the corporatist, centralized military display show it ended up being best known as.