Because each of the cables is a different length, and each of the things plugged into the computer is a different distance to the edge of the desk, and each cable has a different stiffness, and tendency to retain the shape of having been tied up with a twist-tie for much of its life, and so hang off in different ways.
The article better describes why I have to struggle with my earbuds for 5 minutes after they've been put in a pocket.
For what it's worth, when I am transporting cables, I find I can keep them from tangling by folding the cable repeatedly in halves or thirds to make a longish bundle, then tying the entire bundle in a single overhand knot, as if it were a single piece of rope. I've rarely gotten tangles this way; in terms of the article, I suppose it works because it keeps the string from agitating, perhaps even better than using twist-ties.
I picked this method up from a piano teacher years ago, who used it to keep his MIDI cables in order. The result is a bit bulkier than using a twist-tie to bind the bundle, and I'm not sure how good it is for the cable for long-term storage (since it effectively adds a slight twist at several points along the cable's length). But the method has the benefits of being neat, effective, quick to tie, and not needing additional ties/straps.
I've noticed another big factor here is how often & in what order I use all the things I plug into my computer. I use a MacBook, so all the ports are on the left. If I plug in my USB, then power, then audio, etc, every time I do so I pull the wire I'm plugging in to the top of the stack. Doing this often causes the wires to become knotted/woven together.
Anyway, you're right about this article applying more to earbuds, they talk about coiled string in a confined space.
Interesting paper, but I think it has very little to do with cable tangling behind computers. It seems to me that the latter is more a function of manually plugging and unplugging cables over time, where we are manually forming knots--like tying a shoe very slowly.
The main difference I see is that the strings in this study were allowed to move freely, while cables are connected on at least one end, often both.
But they're "not" a tangled mess! If you're a neat-freak like me, you've got everything zip tied down, and some nice BlueLounge.com* cable-management to boot!
*I'm not associated with BlueLounge in any way. I just love their cableyoyo's. :)
The article better describes why I have to struggle with my earbuds for 5 minutes after they've been put in a pocket.