Whatever application you place in the QL area doesn't open automatically and stay open all the time. It is just like any other shortcut you have on your Desktop. Click, (or double click depending on your setup), any icon on your Desktop and the application will run. Close that app down and the shortcut icon will just sit there.
The same with the QL shortcuts. Single click to open whichever application it points to. Close the app down and the shortcut just sits there, forlornly, waiting for you to use it again,
It's just another option, and allows you to open applications quickly without having to minimise any already open windows to find the icon there.
Hope that helps.
When a quick launch icon is placed in the task bar, does it open and sit there "idling" waiting for you to use it? What does it really do?