Under what circumstances would someone need to click the "log out" button?

If I click it, it tells me that I'm logged out, and all my cookies have been cleared. However, if I then click the user cp button, it shows me my user cp screen, without asking me to log back in. Or, "Log Out"==> jump to chit chat, and there I am, my UName is sitting up there with everyone else in visible mode in Chit Chat.

So, of what benefit is it?
-Lou