Do demsocs organize? Yes. Do they effectively work on projects every socialist universally would prefer, unions, universal healthcare, green new deal? Yes

More fundamentally, they're willing to seriously criticize capitalism. Whoever's willing to do that is a comrade. If you disagree with them on methods or policies, you try to have a real conversation with them about that, but you don't refuse to work with them.

What we need to watch out for are Elizabeth Warren types who feign leftist ideas but then reveal they're "capitalist to [their] bones" when pressed.