Paper bags do have a larger carbon footprint, but I assume that parent is talking about plastic waste ending up in the oceans. Bottom line is reusability per your excellent linked article, which paper would edge out on. I do reuse paper bags at least once or twice, but also sometimes reuse plastic bags. I wish there was a way to guarantee that the plastic bag I toss won't end up in the ocean or become aerosolized and survive for a bajillion years or whatever.