First, let me say that the vast majority of people protesting against racists and white nationalists are sensible, peaceful protesters. Overwhelmingly, people standing up to the far-right nutballs are peaceful nonviolent marchers. In recent rallies, the ones who have been armed to the teeth are generally militias there to support the far-right.
That said, the comparably small number of black clad Antifa protestors are playing right into the hands of the far-right. Do you think Fox News (or other cable networks, for that matter) would show thousands and thousands of peaceful people demonstrating against the far-right, or would they prefer to show a knot of Antifa people beating on a Confederate flag-waving Trump supporter? Ann Coulter, Milo Yiannopoulos and white nationalist-types are coming to places like Berkeley because they know they’ll draw packs of scary looking Antifa to run around with their sticks.
I’ve been disgusted with the Black Bloc/Anarchist/Antifa types since the huge marches opposing the start of the Iraq War, when a tiny handful of people choosing violence would derail coverage of an entirely peaceful protest. Unfortunately, they’ve been gaining in number and strength and have become an incredibly useful tool for the far-right.