Because the leadership is through other supporting groups groups like DSA, BAMN, IWW etc. Those under the "Antifa" banner are just the brown shirts for these organizations. I have been to meetings I know exactly how they operate. The end goal is very similar to the brown shirts.

In the brown shirts (SA) there were "large numbers of Communists and Social Democrats" and that "many of the storm troops were called 'beefsteaks' – brown outside and red within."[38] The influx of non-Nazis into the Sturmabteilung membership was so prevalent that SA men would joke that "In our storm troop there are three Nazis, but we shall soon have spewed them out."[38]

The number of 'beefsteaks' was estimated to be large in some cities. The head of the Gestapo from 1933 to 1934, Rudolf Diels, reported that "70 percent" of the new SA recruits had been communists in the city of Berlin.[39]. Other historians contend that the SA and SS were awash with Marxists and socialist revolutionaries, where "The utopians and those who speak of a Marxist republic have the highest membership in the SA and SS (77.6 and 63 percent respectively)."[40]

Some have argued that since most SA members came from working class families or were unemployed, they were more amenable to Marxist-leaning socialism, expecting Hitler to fulfill the 25-point National Socialist Program.[41]

The "beefsteak" name also referred to party-switching between Nazi and Communist party members, particularly involving those within the SA ranks.