Right OP, I looked up that Dissent magazine link and there are a lot of just bald assertions but here's some of the meat:
The EU is relevant here because modern Scottish nationalism is essentially the working-out within Britain of the logic of the EU. Scotland joined the Union in 1707 to enjoy an economic union with a large market and a global trading power. But with the advent of the EU, which guarantees Scotland virtually the same freedoms of trade and movement as the 1707 Union did, Scotland no longer needs to be united with England.
So basically, we should Brexit because that will isolate Scotland to the point where they will be grateful to be in the EU. Great.
The same structures that the eighth president of the European Commission, Jacques Delors, promised to use in the interests of the working class turned out by the time of the 2007–08 financial crash to have been used instead to push through a variety of neoliberal economic and social policies that have only damaged the European working class.
What ones? The ones on parental leave, maximum working time, on protection of occupational pensions, the ones guaranteeing recognition of professional qualifications throughout the EU, the ones on minimum health and safety standards? No, I know, free movement. It's always about free movement.
the creation of the National Health Service, would have been impossible in a country with strong constitutional constraints on the legislature, since it required the large-scale expropriation of private property in the shape of the old endowed hospitals. That is a major reason why so few countries have adopted the NHS model: in most of them it would have been illegal, just as similar proposals would be illegal in the EU today.
I'll take a wild guess that such proposals would also have been illegal in the UK immediately before the EU came into being, and were in fact only possible in that post war period when you were dealing with a country that had had no option but collectivism - rationing and conscription being a damn sight more significant in terms of loss of personal freedom than the requisitioning of a few hospitals. But in any case, this is really on the very far edge of the left wing, is it not? Objecting to EU membership because it gets in the way of being able to requisition private property? I think that is too left wing for my blood.