But as pointed out in the article, JSON isn't necessarily going to guarantee the correct order of your nested bits. Your code is going to have to worry about that. And it will quickly become unmanageably complex. When you are for instance creating a marked up transcript of some archival material, there's a lot of human editing involved. Have a look at the TEI documentation to see how messy it can get.
Certainly. I wasn't suggesting that JSON representation I put up there was actually a good idea, just that it's theoretically possible to represent that document as JSON.