Answer me this:
If something cannot be done with an in-game Addon, and hasn't been specifically given an excemption by other rules/blues, does that mean that it can/should be done with out-of-game addons?

That's called LOGIC.

Maybe I'll add an example:
If delays can't be done with in-game Addons and Macros, and hasn't been specifically given an excemption by other rules/blues, does that mean it can/should be done with a G15 macro?
I've read posts specifically saying that delays are not allowed, so no.

I would like to see a quote about things being done or not with in-game addons in order to form an opinion on your question.

I don't think it applies to keyboard or mouse replication, because neither is available from in-game addons, and both are user input. You can't make an in-game addon replicate keystrokes on your other characters, after all, so does that mean that keystroke replication shouldn't be allowed? The game won't even allow you to cast a spell without a button down, so you can't just send a message to someone and their addon immediately pick it up and cast a spell. Key replication can be used at the login screen to type the same password for your accounts if you use multiple accounts, but in-game addons cannot be used at the login screen. Thusly, I don't think that INPUT REPLICATION is bound by the ADDON RULES, because input replication is at a higher level than the game is, and I don't think that to say that because an addon cannot click, that your mouse or mouse replicator should not be able to click, would be appropriate. Nor do I think that to say that because an addon cannot press a key for you and have it type into the chat window, that a keyboard or replicator cannot press a key for you, would be appropriate. Rather, user input actions may cause AddOns to perform an action, or do something else in the game (edit: And this is SOLELY due to World of Warcraft interpreting those user inputs and performing the action).

ClickBoxer is not part of the game UI, nor does it directly interface with the game UI. It presses keys when you click a button.

Repeater, again, is replicating user input actions. It does not interface with the game UI, it presses keys when you press a key, or clicks when and where you click. It does the same clicks that are available to your mouse.

When a Blizzard poster talks about AddOns, and I will note the capitalization of the O, I would take that to mean in-game interface AddOns. Anything else would typically not be referred to as an AddOn, to avoid such confusion as in this thread. But, for the purposes of this retarded argument, I will bite. It could very well indeed be taken to mean "anything added on" such as software like ClickBoxer or KeyClone, or hardware like a keyboard or a mouse or a monitor or a joystick or a gamepad. So my keyboard and mouse may not change targeting? How far out of context shall we take AddOns?