Why are reviews deleted when the OP's thread is closed? Simply because the OP didn't post enough reviews to be allowed to post for review, why delete reviews when the thread is closed? If I were to post something up for review, now, it'd probably be closed since those reviews I put effort into have "vanished." If I hadn't caught on to this, I wouldn't know, and would be pretty upset when my own thread was closed.
The reviews are "soft deleted", which basically just equates to being hidden. They are still there, and they still count in your post count and towards the number of reviews you have made, but they are hidden, until the OP fulfils the required number of reviews. Simply put, someone making a review isn't penalised for an OP's failure to abide by the rules. I hope that clears things up for you.
The reviews are soft deleted, as Banzai said, so that the original poster doesn't profit by the reviews he or she happens to get before the thread is closed. If the returns and fulfils the requirement, the hidden reviews are restored. As mentioned, we still know what reviews you have completed.
Ah...that answers a question I've had for awhile. I always check back to make sure the OP has done their prerequisite reviews before I read their story--if they only have a few posts that is because I was in the middle of a review once and when I went to post it, well you know what happened. I've been wondering why some stories haven't been closed when I couldn't find the OP's reviews. Thanks for the info guys.
Thanks for the answers. Definitely clears things up. And yep--I know what soft delete is. Use it all the time where I come from.
Oooh. Glad I checked this thread, since this just happened to me. Too bad, I thought it was a pretty well-done review. Oh well, I'll prod the OP to review a couple of things herself, maybe it will come back.