When I'm looking in the deletion log on a wiki some of the pages are deleted because of "housekeeping". I still don't really know what does it means though.
"Housekeeping" is just a generic excuse used when we delete pages.
In case you don't know, mods often sweep the forum to delete any pages that might not pass our quality standard. Many mods (not me) are very strict and often delete any pages that they consider bad.