People may only travel up one or down one level from the Giftworld they were born in, or they will become Untethered, a scary fate. If there are many Giftworld connections present that are only one level down, people could theoretically visit many worlds without becoming Untethered - although these connections would need to be reachable, which is very unlikely in our scenario, as the Giftgates are carried away into the Wastelands shortly after creation.