Rockhopping was invented as a practice at some point in the early years of interstellar flight in the Ecumene, perhaps as early as the year 200. The most common story of its invention states that a way to supply the new colonies in Nesevity system was sorely needed, as skip drive ships were slow, small, and simply couldn't make the 3.6 light-year journey from nearby Sadel. Even as large "decader" ships were being built, a solution was found: even substars have clouds of small bodies orbiting them to a wide radius, and beyond those clouds deep space bodies remain common. With planning, even a hop drive ship could travel long distances... at a price. As tests were carried out within the Ecumenical Cluster, it became evident that the hop drive did not take well to bouncing between tiny rocks. Mishops placing ships astronomical units off course were common, and trying to go both ways without a tune-up guaranteed a drive failure or two.
As such, first expeditions using the rockhopper method are not as easy as might be first assumed- the amount of pre-planning can amount to setting up cities on dozens of interstellar bodies. However, rockhopping is extremely good for supplying cities or other expeditions that have actual industries, especially if they're capable of building FTL drives. The rockhopper method has carved out a niche for itself- where STL is too slow and FTL can't go far enough, rockhopping can bridge the gap. Few systems have been inhabited or even explored directly by rockhopping- with the prep time required, it's only harder to go by STL when the 3D distance is much higher than the 2D distance. Even so, rockhopping has been invented almost as often as FTL- first contacts have been caused by rockhoppers meeting each other. In the modern day, nearly all of the systems of the Ecumene have some level of presence on nearby deep space bodies- for more than being a supply method, rockhopping has emerged as a way to stop and smell the roses.