The scrapbox is... Ergh, I'll hate saying this... Unmoderatable, from what I have seen, due to all the constant SPAM. IF idiots didn't keep posting stupid requests, or SPAM, then perhaps there would be an idea to save it, but... Now I think about it, there is 1 thing you could have tried - Approval Only for Scrapbox. True it will mean more threads need approving, but less SPAM, and the same idiots who broke the rules will probably do the same for Progressing Hacks.
Thats a great solution (although i believed i already mentioned it.) Making approval before posting the thread will reduce spam. It will get rid of ALOT of threads that don't meet the requirements of the scrapbox I.E: Some hacks are closed because they don't contain a storyline/features list/or other info
BUT now I think about it, you probably considered it (but nice if you had at least tried it before, but there are more cons than pros... You made your choice)
So... The problem is rule breaking, which... May occur more elsewhere.