You can do that by rendering text yourself, particularly in a full-immersion app. Rendering distance field text is cheap and really easy to do properly in that situation, but I don't know if anyone has actually done it in practice.
It gives a pretty good summary and a lot of other vocab words you can google, and touches on the Pathfinder project
IMHO, that's another dead end (or rather intermittent tech), like full-screen apps, or single task environments (hello, DOS).
Either way he should be ashamed of himself!
Most productivity apps, however, have their own way to subdivide space within the app efficiently. E.g. in the IDE, there are various panes and tool windows. Put a file browser on one side, a documentation browser on the other, and a terminal pane on the bottom, and it actually starts feeling kinda crowded.
Sure, some people will want to tune out / turn off all other apps from time to time but the ability to run them together is really key it seems.
I wish browser VR supported popping 3D things out of the screen. Currently browser VR is click a button, browser display's that page's VR presentation in your VR. But run one of the many VR virtual desktops that show your computer's desktop as a virtual monitor in VR and suddenly I want a standard so that a webpage can make a 3D object and it pops out of the virtual monitor. Ideally like a browser tab I could pop out lots of different VR-VR apps/pages/etc all running at the same time, all integrating in the same 3D space.
(Something I don't think a lot of people notice, too, is how important 3D is to the Fluent Design System, and not just for Material Design reasons of faking paper stacks for visual interest in 2D, but probably because a lot more of Microsoft is taking 3D very seriously than it currently seems obvious that they are given the current intentional "no hype" approach.)
It certainly sounds like the Windows team has been thinking about all of this sort of stuff for years now, and I'm very curious to see a lot more of it come to light rather than just "we're thinking about it". This article also hints at some more of it getting released as real services SOON™.
I'm presuming we'll hear a lot more about Azure Spatial Anchors at this year's BUILD, and that could be quite interesting based on the hints in this article.