- You can only compress 1 item at a time (selecting all items with the tickbox is irrelevant)
- You cannot compress the www folder
People would want this so they can backup their website only (excluding emails accounts which could be large) maybe to put a copy locally for messing about with.
For reference
All Ticked
Create Archive (this will only compress the test folder even though all the items are ticked)
No option to compress