> In particular, the convention has been established that the GET and HEAD methods SHOULD NOT have the significance of taking an action other than retrieval. These methods ought to be considered "safe".
(there's an exception listed too, but doesn't apply to logout)
EDIT: I know of someone who made a backup of their wiki by simply doing a crawl - only to find out later that "delete this page" was implemented as links, and that the confirmation dialog only triggered if you had JS enabled. It was fun restoring the system.
I don't know why you think I'm contradicting them. I was just pointing out that there are newer RFCs. They also happen to have a stronger and more complete definition of safe methods.