TBF Howard Zinn has a rather pessimistic view of class struggle in the US and that is reflected in his book, at least in my opinion. In emphasizing that radical movements have always been crushed, deflected, or co-opted by the political elites he implies the inevitability of such outcomes and often misses some of the ways that those movements still succeeded in radically altering the class arrangement, and the experiences of those who lived quietly in the crossfire of these historical struggles are erased through omission. A lot of that is an understandable limitation of an attempt at an all-encompassing historical account though.