Well, "on top" is always relative. This dune is significantly lower than many of the surrounding dunes. But it's the highest one, and one that's also popular with large-scale sliders. This is probably because there are no obstacles (like rocks or bushes), it's steeper than other dunes, and, above all, it's quite close to the parking lot—so it's easily accessible.
While it's certainly ideal for sliding, many of the other dunes are better suited for hiking (it's easier to get up and down there on foot).