Certainly all are encouraged to write down their thoughts and then post them. Somehow, posting and reviewing got connected and that would seem like mixing apples and oranges. One needn't have to do one in order to do the other...To restrict reviewing to only those others who do make the move to post their story(ies) would seem to severly limit the scope of feedback.

As each writer has his or her own point of view, that may tend to unduly influence their reaction to another's work. With so-called lurkers they have no such limitation and view each piece they choose strictly on their own merits. If these readers then choose to post a Review, then so much the better.