I think it can still be appropriate to criticize the original source (even publicly), without appealing to the intermediary. ("Amazon is allowing sellers to sel

I think it can still be appropriate to criticize the original source (even publicly), without appealing to the intermediary. ("Amazon is allowing sellers to sell t-shirts promoting rape!"... Rather, Amazon is simply allowing sellers to sell. The products are either legal or illegal. If they are legal, Amazon would be discriminating by not allowing the seller to sell their goods...)