Yes, and private messages should remain private (and hopefully searchable). Balkanized data isn't necessarily bad, and there are lots of shades of grey there.

Yes, and private messages should remain private (and hopefully searchable). Balkanized data isn't necessarily bad, and there are lots of shades of grey there. As two examples, though, if the only way to search Twitter is Twitter, and Twitter won't let you search for tweets older than a week or two, then you're out of luck. More hypothetically, if most people used Wordpress for blogging for the last 15 years, and Wordpress didn't allow indexing by search engines, but only searching on Wordpress.com, we would not have the internet we have today.