I can certainly understand this assumption. I get confused by features that appear to do nothing when I enable them. "Does that actually work, or is this a bug? Under what situations does it actually do something? Why is the menu option available, when other no-op menu options are greyed out, eg Undo when there's no undo stack?"

Anyway, I don't see a huge need to fix the guides' behaviour, and am certainly opposed to the functional changes suggested at the start of this chain.

However, a simple fix for this and other similarly not-immediately-obvious functions could be to display a notification giving the reason why the feature doesn't appear to do anything. Eg "There are currently no guides in this document. Click and drag a ruler to create one." The message/status bar at the bottom would be appropriate for this (not a popup dialog!).

On a tangentially-related note: I believe there should be the ability for certain features to be able to highlight the status bar on various messages, perhaps with a brief orange pulse, to draw the user's attention to it. I'm always missing the useful messages in it, even though I'm very much aware of its existence. My classic is to try and draw onto a hidden layer. Try again. "Why isn't this working?" Try again. Again. Oh, "Current layer is hidden"...

 - Bryan