Or perhaps to refine that, to scoop important patents
Apple is aggressively out there patenting obvious things that have been basic public knowledge / in use for years to try and lock up the field (eg: [0]). You can try and get your own patents but if you aren't strategically dependent on the IP for your own needs it is much easier and quicker to just nuke the field by putting as many things in public as possible so it's much harder for Apple (or others) to retro-patent broad classes of obvious features.
[0] https://image-ppubs.uspto.gov/dirsearch-public/print/downloa...
Like this quest app for visualizing wifi strength in mixed reality.
Blurring can be applied, but that doesn't change the physics that your eyes expects, which causes the disconnect and discomfort, which varifocal displays solve.
Apple has actually issued developer guidelines for AVP that Apps should only render UI / static content at a fixed position from the headset in space corresponding to the fixed focal distance for this reason.
My assumption, of this early work, is to scoop up important patents.
Related to important patents, varifocal is almost certainly the future of HMDs.
Having fixed focus, as all HMDs do now, is fatiguing and strange. A really interesting example of this is, in VR, hold something close to your eyes. You'll see that it gets blurry. Now close one eye. You'll see that it's clear. It's not that it's actually blurry, it's that your eyes are refusing to put up with the physical nonsense of a fixed focus 3d world.