I think this is close, and the video touches on that as a characteristic that’s contributing to this, but there’s a motivation left unaddressed by the video that needs to be called out:
Reducing depth of field reduces the render resolution, which reduces the costs of digital processing and generation.
The simplest way to demonstrate this on a desktop computer is with the photography mode in games like Minecraft or Satisfactory or Elite Dangerous or No Man’s Sky, where the user can modify the Render Distance and Depth of Field at will. Load up the game viewing some planetary scene and enable the fps counter, then start changing the render distance; the closer you set it, the faster each frame will be generated. But the background will look defective and empty, so add depth of field, and now it doesn’t look so cheap — and when you take the photo, depending on the game, it may override your realtime render distance because it can take five seconds (!) rather than 1/60th of a second to generate that frame at 20 megapixels.
I think that the shift towards low depth of field in movies is, in part, a reflection of cost pressures, especially in 99.9% CG movies like Quantumania. And I think this is where Avatar beats out the competition for pure CG worlds in this video, because it renders at full resolution. It must have cost significantly more to produce than Quantumania (yep, $250m > $180m). I wonder how much of that difference was due to rendering the entire movie with a cheapness DoF blur. If nothing else, shadow rendering is so much of the difficulty of CG, that it could plausibly alone be the reason.
(I think that low depth of field is also currently popular because mobile phones lack it, and so producers are consciously or unconsciously selecting for an experience that is distinct from what they might film on their own. Depth of field is a very cheap form of escape.)
I think that is the wrong lesson to take away from the video. As the video emphasizes, DoF is a tool that can be used to achieve an intended effect in story telling.
Main thrust of the video is that these days these tools are predominantly being used for convenience of post-production and cost cutting at the expense of immersion and story telling.