I've never heard of that or seen it, but I don't have any objections at all. If it means I have more things to look at and be inspired by, I'm all for it! I don't think they belong in the same category as completed quilts if it's a judged show, but I don't have a problem with tops only being put on exhibit or being judged in their own category. Particularly if they're vintage tops where the original piecer has passed on or is unknown.
Looking at the backs might even be interesting, might spot an interesting technique!
(I'm 40)