But where would we be if every little question asked and answered vanished into the depths of Zuckerberg's private network? What if, one day, you wanted to look up that strange error message your computer was giving you (or, to take a more life-and-death example, imagine you needed to know how to cook a haggis) and the only results that came back in Google were those spam sites that are increasingly clogging up the internet - because no-one was talking on forums or contributing to public comments any more?
No doubt there's also a lot of text stored in Facebook that is of no value whatsoever, and the internet would be a poorer place for having it, but that's the job of search engines - sorting the wheat from the chaff.
Not only is text vanishing from the internet, but so is information about that text. If hyperlinks to interesting content are increasingly shared via non-searchable social networks, then search engines will be increasingly starved of information used to determine what is popular or useful. Facebook delivers a double blow to the internet - not only is it siphoning off content, it may also be making search engines less able to sort the information they already have.
This is true for any website that uses IntenseDebate or Disqus to facilitate user comments (unless the website owners use a workaround to gather the comments from the remote server and render them into static HTML). All those comments are falling into a black hole. That might not always be a bad thing, but there are almost certainly things of value being lost. Comments often provide useful information that the article above them missed. In fact I'd argue that much of the Guardian's online journalism in the past seems to have relied on it.
Not only are these black holes of the internet sucking content and information out of the free internet, but they are sucking away money. Advertisers are increasingly moving their expenditure to Facebook. Companies are increasingly moving their interactions away from their proper websites and towards Facebook, perhaps neglecting their web development. That's not good news for web developers and it's not good news for the internet in general.
If Facebook and Twitter were to vanish overnight then I guess popular websites might see a sudden surge in commentators That would not be without its problems, but I think they could be overcome. I might set out my solutions to those problems in a future article.
There is a huge danger in the direction the internet is taking at the moment. The fewer indexable public comments and forums there are, the fewer people will find and use them. This will create (and perhaps already has created) a downward spiral of fewer and fewer genuine users. This will leave the field wide open for people with agendas to hijack all the mainstream communication channels. People such as marketers, journalists, lobbyists and the government. I strongly suspect it is already happening.
Do we really want the internet to turn into Television 2.0?