Collectivism always helps those below the median and harms those above the median in whatever metric you are trying to mediate via collectivism.
Collectivism is typically preferred by people below median in whatever metric you are considering.
Collectivism is typically preferred by people below median in whatever metric you are considering.
So, in that sense, OP is still correct - it's beneficial for workers to organize for collective action, so long as you draw the proper boundaries within which that collective action will operate.