No, there is a difference. An old book at the brink of extinction still belongs to you. You can get third party services to preserve the book for you with the stipulation that your preservation work and the book carries decent privacy rights (it won't be broadcast to the world what you're doing). Remember the old days when you would go to a store to develop your camera roll? The service implied that your picture content is between you and the developer of the film.
It's fine if people don't see any privacy implication here by submitting their reading collection. But as far as my single individual point is concerned, I don't see why I should upload my OPML for the sake of preservation. I have hard time uploading it to any other Google replacement out there trying to compete.
Oh, so you're not really worried about people downloading the content of the blogs, you just don't want anyone to connect the list of blogs to you? Well, you can just take the URLs out of the OPML file, and submit them one at a time. You can even use different IP addresses if you're that paranoid.
