It doesn't, but it gets around the extra overhead you get with the added metadata.

OO on its own is slower to parse than plain text, but binary is faster to parse than plain text. If you combine the both can you get the best of both words, something that's both reliable and fast.

I see that binary might be interesting. But why add OO to the mix? There are other worlds to mix the best from.

As one silly example, you can consider Google's protocol buffers. They are not particularly OO-y. (I have great sympathies for functional languages, but I don't think they offer too much insight into how to format your data files. And neither does OO?)

It is a "enemy of my friend is my enemy" sort of thing, the minimization of a shortcoming. OOP stumbles on text (because of object methods) in a way that no other programming paradigm does. So obviously that means that text is stupid and we never really liked the benefits of text anyway!