On-axis frequency response is one of many characteristics of a speaker. And since they
reviewed the set of speakers as a set, and not those speakers individually in that
review, the surround channel speakers don't matter so much, and so they will be a relatively minor part of their overall opinion of the set of speakers. I could also add that magazines that take advertising typically are cautious in the way they
review things, because they do not want to lose advertising revenue, so that one needs to pay attention to subtle details of the
review in order to judge their real opinion.
By the way, I am
not trying to convince you that you are wrong to dislike them. I am merely trying to answer the implicit question in your final sentence.