As a device that's essentially a smartphone with some extra hardware/custom software, I would imagine that's like asking "what has Apple done to lock the iPhone to iOS?" or "what has Sony done to lock the Playstation to only run Playstation software?"
If you think of it less like a monitor and more like a game console or a phone with a locked bootloader, then it's easy to see how you can require account auth in order to use the built-in software.
I recall that being the case when I had an old gen2 iPad and wanted to do a few things that weren't sanctioned/supported by Apple. There were a few well-known repos for homebrew software and that's where I got the handful of useful tweaks and customizations for that (jailbroken) tablet.
I guess the issue there is that the popularity of the platform and nature of its limitations made it worth someone's trouble to maintain those repos. With something like an Oculus, I don't know that there are enough users (and also a sufficient subset that want to avoid Facebook or run some unsanctioned software) to justify the effort.
If you think of it less like a monitor and more like a game console or a phone with a locked bootloader, then it's easy to see how you can require account auth in order to use the built-in software.