Hoisting shows only one branch of the tree. Filtering would allow you to see select items (like a Search) but in their appropriate hierarchy rather than as a flat list and since they are displayed in the tree, allows you do all the linking, expanding/collapsing, etc. you can do with the tree view. It is discussed at length here:
http://www.kinook.com/Forum/showthread.php?threadid=721
and here (starting a few posts down):
http://www.kinook.com/Forum/showthre...&threadid=1391
The simplest example to understand is hiding items marked Completed. But there are many other useful ways it can allow you to focus on a subset of your data that doesn't fall under a single branch and without recreating every view that you want with excessive multilinks.