User blog comment:GrandMethuselah67/Lore Sheet: The United Republic of Humankind/@comment-4867780-20150705091736/@comment-4867780-20150709232850

Not all grown ups leave their parents, but most definitely do. Some follow similar rules, others much less so, but it is their own and no others'. Even if they don't materially need to leave and still love them very much, they psychologically need to become their own person.

The mere fact technologies are available to everyone all over the Republic proves there's no monopoly to use as leverage. As for resources, the matter-conversion capabilities of said technologies basically removes such a need, so each community seems pretty much self-sufficient.

So while they may not have particular reasons to secede, they may simply want to become their own collective "person", especially since technologies have allowed communities to grow extremely different in the pursuit of their own understanding of "perfection", and that "independence" may have become a key aspect of it for quite a few.