Most of that is true. However, some ARCs or proofs are produced in such quantities that they are worth less then the actual book when it is released. One example is LISEY'S STORY by Stephen King, which I believe had thousands of ARCs produced. Much of the value of an ARC price has to do with the author and scarcity of the proof combined.

Also, TOR has done limited editions. I have six signed and numbered books from Orson Scott Card that TOR released, and I assume they've done others.