PublicityA political term for the fact of information getting published, that is, being made available to all. Some reasonable fee may be charged for the energy (media, shipping and handling) spent while transmitting information, but publicity means that the information itself is free. This is basically the meaning of what the Free Software Foundation calls "free software": software that is public, and (in the case of GNU GPL'ed software) cannot be stolen from the public (which is not the case of "public domain" software).
Publicity is independent from centralization; surely, in a public system, identification, authentication, and arbitration require as much (and as few) centralization as in any other system. But publicity is about spreading declarative information for individuals to take their own decision, not about spreading imperative decisions for individuals to obey. Because with generalized publicity, information proceeds from a center, people often mistake it for centralization, whereas the two concepts are opposite: with centralization information goes toward the center, then decisions come out of the center; with publicity, information goes out of centers (nothing prevents multiple editors to coexist), and decision is decentralized.
The main problem with publicity is the noise induced by anyone publishing anything, which most of the time is devoid of any interest, or redundant with much clearer works. This noise makes useful the small overhead for information publishing and receiving, because such price is a means to select meaningful information.