Also, they had mayors and stuff, a VERY clear class division and were technically under the rule of Gondor after the Northern Kingdom fell but Gondor didn't really have the resources or urge to do any ruling over there. Once Aragorn was in they were essentially an autonomous zone under military protection in exchange for maintaining the local roads and bridges.
I also once wondered about it so guess this isn't such weird question if we came to it independently. Both the existence of Shelob and spiders in Hobbit seems to support it as clear hierararchy of decline of spiderkind, like other species in Tolkien universe also decline in time and generations. Maybe Tolkien just hated spiders, i do know that fragment in Hobbit is the hardest part to read for me out of entirety of his works.