Having combined a series of prompt-response oneshots into a single story, I had the opportunity to see all my reviews together for the first time, and I have to say, I'm delighted by the number of reviews that contained concrit. It was all valid, and I did take what was said to heart and tried to incorporate that into future prompt responses. Hopefully, I did grow as a writer.
But that is indeed the issue. The concrit was balanced. There was comments on what did work as well as what could have worked better, or didn't work at all. When I can't find a single positive thing to say, or when I'm confronted by something that requires multiple attempts to make sense of a single sentence, I can't find anything positive to say beyond, "I'm so glad you were able to turn on your computer."
I don't do polite lies, and if I couldn't get more than a paragraph into a story before I walk away, then I also feel no obligation to leave a review. What could I say, after all? "I read a paragraph of this story and was unable to continue." Anything further delves into the realm of being unnecessarily unkind, and as a member of the staff here, it is both inappropriate and inexcusable for me to leave such reviews.