> I'm not sure how the concept of tracking virtual islands over the horizon really helps. The only thing I can think of is maybe the idea of it encourages the navigator to stay focused on estimating the passage of proxy points on the far horizon
You can practice navagating against physical islands over the horizon, and when you're good at that, you've mostly gotten good at dead reckoning against a real reference point; of course, with corrections from the islands influence. Having a community shared archipelego of virtual islands lets you focus your dead reckoning skills on a point while offering a vocabulary of distance and reducing travel times between waypoints.
Go 1000 miles in this direction seems a lot harder for me to follow over many days than go X miles to A, then Y miles to B, then Z miles to C. Even if A and B aren't real. If I treat them as very small islands that will be over the horizon, no big deal that they don't influence the environment, they're small; but I can't really use them to course correct, my reckoning needs to be good.
You can practice navagating against physical islands over the horizon, and when you're good at that, you've mostly gotten good at dead reckoning against a real reference point; of course, with corrections from the islands influence. Having a community shared archipelego of virtual islands lets you focus your dead reckoning skills on a point while offering a vocabulary of distance and reducing travel times between waypoints.
Go 1000 miles in this direction seems a lot harder for me to follow over many days than go X miles to A, then Y miles to B, then Z miles to C. Even if A and B aren't real. If I treat them as very small islands that will be over the horizon, no big deal that they don't influence the environment, they're small; but I can't really use them to course correct, my reckoning needs to be good.