I think they're saying "If REI makes the list because this is common in the space, what is the benefit of worker owned?" in trying to bolster the case that REI should not be listed.

If many of the worker-owned co-ops would prevent access to relevant customer data to prevent individual workers from developing relations with customer without the co-op in the middle, then that's something that could potentially be addressed by other co-ops in that you could deliberately structure it such that the co-op is either optionally or deliberately a platform for fostering worker/customer interactions rather than co-op/customer interactions.

Because if the co-op exists for the sake of the co-op while splitting profit with the workers, that is different from a co-op that exists solely to maximally aid the individual workers.

Kind of like the back/front of house tip debate. Should chefs be payed as tipped salaries? Should we all get regular wages and evenly split tips? Even in front of house, if Sarah is consistently pulling twice my average tips, it's not really fair to her (or technically her customers) that we split tips because the customers were so taken by her service that they wanted to assist her whereas I'm just some random person from their point of view and contributed nothing to her customers from her point of view. The analogy is that the company wants to split the tips because it benefits them by allowing them to more easily retain employees in situations where they feel it's worth keeping the ones that aren't getting big tips because their performance is "good enough" and they don't want the spend on hiring to replace - the benefit is too the company and the 'worse' wait staff, not the one who's actually responsible for the value add.