Yes, its a tricky issue. Actually, from what I know, it has become a "bad" habbit to use exactly what we would normally find good, to drive up the prices. Collectors lend their art to museums. Alright now, thats not so bad, if it was for the reason to share a special piece of art with the public. Plus, the museum doesn't have to come up with astronomical amounts of money to get these artworks.
Thought behind it is, that any artwork, which was shown in an (important) museum experiences an extreme increase in value. In this case, Ms Oprah just used a proven method. Leaves the question, of what the intention of the new owner is... so far I don't think its to drive up the price (see above ;-) )
This is really fascinating! I would never have known this at all because, you're right, it seems counterintuitive. Thanks for such an educational comment!
You are very welcome, thank you for your attention :-)