I'm not saying they're the only ones doing anything or even that they're doing the most or that they're doing it alone. Go to any leftist event and DSA is there almost regardless of the size. At least in my city they do a good job of bringing members to events and letting the events happen: they aren't taking the event over they're just ensuring people are there. DSA turns people out, and that's I think their biggest value and why I say they're so important. It doesn't matter how many events your Marxist book club puts on if nobody is there, but if you coordinate with DSA you can be sure people will be there