Sure, you can put A, B, C, D side by side. But next time if you need to find D, you have to navigate A > B > C > D, with no other recourse. Often, you don't c

Sure, you can put A, B, C, D side by side. But next time if you need to find D, you have to navigate A > B > C > D, with no other recourse. Often, you don't care about A, B, or C. Only D. And the benefit of A, B, C, and D being close together becomes immaterial. In real systems where things are spread, A, B, C, and D can be very far apart indeed. And it's totally fine! What matters is that from the starting position,let's say X, I can 'navigate' to A, B, C, or D, in an equal and speedy manner. Plus human brains love to navigate things in a 'spatial' way like this. It's natural. Really when you think about it, the perceived loss here is not that big compared to the benefits.