I do have a private forum I've set up as a duplicate of my own forum and it is indeed private for the reasons you give. I use it as a testing ground to make sure what things will look like before going to press with them (LOL).
Also, in our "real" forum, we do have access to make folders private -- e.g., I have a staff folder and archives folder that only my staff persons have access to. JQPublic never sees those as there is no need for them to see those. My guess if different forum umbrellas have different setups for "hiding" folders or making things private, but I love being able to easily give "permissions" where they're warranted.
Also at my place, we have an option to keep the spiderbots out if we so desire -- and I do (wink)!
-- 18 Apr 2015, 21:28 --
Smiling at Cookies' post -- when that happens to me it makes me all the more determined to want to join -- just to see what's behind those closed doors ------ unless it's Xrated, then I shy away! 🙂