In the old days, when UUCP over long-distance dialup lines was the
dominant means of article transmission, a few well-connected sites
had real influence in determining which newsgroups would be carried
where. Those sites called themselves "the backbone."
But things have changed. Nowadays, even the smallest Internet site
has connectivity the likes of which the backbone admin of yesteryear
could only dream. In addition, in the U.S., the advent of cheaper
long-distance calls and high-speed modems has made long-distance
Usenet feeds thinkable for smaller companies. There is only one
pre-eminent UUCP transport site today in the U.S., namely UUNET. But
UUNET isn't a player in the propagation wars, because it never
refuses any traffic---it gets paid by the minute, after all; to
refuse based on content would jeopardize its legal status as an
enhanced service provider.
All of the above applies to the U.S. In Europe, different cost
structures favored the creation of strictly controlled hierarchical
organizations with central registries. This is all very unlike the
traditional mode of U.S. sites (pick a name, get the software, get a
feed, you're on). Europe's "benign monopolies", long uncontested,
now face competition from looser organizations patterned after the
U.S. model.