If you look at the video I posted at least one professor seems to think otherwise and I kind of find his arguments at least worthy to consider. Corporations will by nature have place an emphasis on pleasing owners, which in the case of coops are the workers. So, it doesn’t dispense with competition in general but aligns interests better with workers which should have a profound effect on “coercive economic relations”.
If you just mean that coops just cannot really compete, I would say that’s a myth. Look at Mondragon for example [1] or some large German coops. They also run successful competitors to walmart at leasr in europe. I think that one reason that they are just not as common is a general need to raise capital quickly, general availability of capital and a lack of education. But you are right that none of that is likely to counter an existing monopoly with access to huge capital baring some kind of legislative changes. There is certainly a place for unions.
1: https://en.m.wikipedia.org/wiki/Mondragon_Corporation