So the only important bit is to educate people on the apparently simple concept of magnification.
At the very essence of all this is:
1. How big is the object as you now see it in relation to how big it is in real life.
2. How big was the aperture opening.
The first allows for everything involved in the reproduction; focal length, distance to object, coc, sensor size, crop, print or screen size, and viewing distance. Each of those affects the magnification. Plugging these values into a dof calculator just allows it to calculate the magnification taking the print or screen size and viewing distance as standards for a set CoC, some calculators actually allow you to change the CoC and magically your DOF changes, even though the image is already taken.
The second dictates the amount of blur in relation to the magnification.
Hyperfocal is a side issue with no merit, stuff falling within the hyperfocal is still not as sharp as the plane of focus. magnify it the same and it is just as blurred (try it with the images on the LL link, I did for a thread a long time ago). Indeed lenses marked hyperfocal scales are historically at least one stop wider than accepted norm CoC figures because they used a different value to calculate them. But the important bit is that hyperfocal is just another manifestation of magnification, it isn't sharp, it is just small enough to give the illusion of sharp.
It is all about the illusion of sharp. The actual plane of focus is always at it's thinest, which is the diffraction limit of a lens. However, when the CoC becomes as small as a single pixel of your camera sensor, it is perfectly sharp from that point and smaller. That's how you gain the depth (of field ). You will cross the line when it is impossible to magnify it enough, because the resolution is too low.