The bottleneck for adoption is probably mostly about UX, comfort, norms, marketing, etc. Not raw capabilities.
The uncanny valley on the raw capabilities of these current products is a grand canyon. Holodeck it ain't.
There is a limit and a point where this can make things worse, but if it approximates what a person expects well enough and never conflicts with that expectation it’s a good tool.
Mobile phones offers people a very comfortable and easy UX that blends well with the requirements of the real world, you could say it does it too well as you often see people walking down the street faces glued to their screen and not looking where they're walking.
VR needs the power of immersion, but right now it comes at great cost. The friction of entering and exiting is big, the time between task switching of virtual and real is big.
You mentioned this:
> In VR you multitask by bringing the computing environment into the virtual environment. So there is no deficit there.
You cannot and bring all required tasks into the virtual. You can't quickly check on your dog, grab a drink, glance over to a person in your physical space, grab that note from your desk. We rely heavily on the real world and VR right now presents a big barrier. Phones do not, you can watch a movie on TV and glance at the message that pops up on your phone. Even desktop computing allows you to comfortably multitask by glancing between monitors. Some stuff can bring virtualized into VR windows, but it's limited.
I exited VR in 2018 after a few years of working on it. My conclusion was that we're still too early to get bullish. We still need to overcome some big technological hurdles that bridge the gap between comfortable and complete immersion (100% audio & visual simulation), a blend (AR), and 100% real world. We also needs to better address other immersive factors such as haptics and interfacing, because as you increase the potency in one area (visuals) the requirements in other areas start to rise as the playing field demands completeness or risks breaking that desired immersion level.
Even without those technologies current VR is quite different in terms of social presence to interacting on a flat screen. A lot of body language comes through even just tracking the head and hands.
I think we’re quite a bit away from having mass adoption of VR though. But that’s more form factor and comfort.