To start with, I will note the vast majority of large aperture shallow DOF images show far stronger OOF effects than we would see when viewing the same subject "live". There are exceptions like the extreme example above of viewing or photographing our finger tips at "macro" range, but most shallow DOF shots are not like that (See more on that case below). Indeed, the classic example used to denigrate "formats smaller than the one that the speaker prefers" is portraits, so I ask: how often do you look at a person and see the eyes in sharp focus both the ears blurred? (Let alone seeing one eye in focus, the other not.)
But there is another simple physical factor rarely mentioned: our eyes have smaller apertures than most lenses. The lenses in our eyes have a focal length of about 17mm to 22mm, and in decent light the iris opening is about 5mm or less, giving about f/4, going down to about 2mm and so f/10 in bright light. [The opening is up to about 8mm in dim light, so you will see that maximum figure quoted for the human eye, but that extreme does not occur in typical viewing conditions, like daylight or reasonably well-lit indoor locations. Moreover, when our irises are that wide open, our vision is significantly degraded by lack of light and lens aberrations.]
If we consider the part of the image on the retina considered as our "normal" field of view excluding peripheral vision, so a region about as wide as the focal length, our eyes are effectively in a format with roughly 20mm frame width, so about 4/3" to APS-C format. Thus we have DOF comparable to a 20mm "normal lens" in such a format. Converting to the old currency of equivalent DOF in 36x24mm, we get something in the range from 30mm and f/6 to 40mm and f/8. If instead you use the extreme 8mm figure, our eyes' lenses are roughly 20mm f/2.5, and the DOF corresponds to something like a 30mm f/4 or 40mm f/5 in good old 35mm format.
Conclusion: the lenses in our eyes give OOF no stronger than typical kit zoom lenses in formats 4/3" and up ... and that is before eye movement and the sophisticated "image manipulation" done by our brains create a perception with diminished OOF effects. This still applies in extreme cases like viewing or photographing our finger tips at macro range: most kit zooms will still give as much or more OOF effect there as we see "live".