It´s probably not necessary to be quite as strict as they are, but to be honest, I appreciate the distinction. When I´m bored I sometimes go through the tags on genrefinders to find stories I´d like to read, it´s quick and easy. I´d never do that on storyfinders because that one story someone remembered a tiny detail of doesn´t really interest me.
(I do think that answering a request at genrefinders with "there was this one story and it went like this" and answering should be allowed, because then the original requester can do the extra-work of asking for it on storyfinders himself, or else if someone recognizes it there it keeps dual posts down.)