DNS is a more of a hierarchical system, where the roots are at the center, and they delegate trust and responsibility as necessary.
Also, in my view peer-to-peer supernodes do not monitor or forward all data, they only maintain address information of the peers (rendezvous as you say). DNS, as it is implemented on the public internet, is ripe with passive monitoring as all data flows through centralised points in the tree. Leaves, at the network's edge, are expected to be "dumb", needing to make hundreds single requests for the same information, 365 days per year, even when the majority of it is relatively static.
Every query and response packet containing a seemingly useless "Query" field that never varies from "1". There's no pipelining (when using TCP) or packets containing more than one query.
From what I understand there was interest in so-called "P2P DNS" in reaction to various incidents of censorship via the centralised points in the tree. If the leaves were truly connected as "peers", and sharing the database data directly "peer to peer", then we might have better protections against censorship.
Incidentally, "DNSSEC", as advertised, appears to anticipate centralisation and usage as a CA-like system where peers at the network edge are not only dumb but incapable or verifying messages themselves without involvement of third parties.
In contrast, encrypting DNS packets requires no third party assistance. It can be done by peers all by themselves. A client can encrypt queries and a nameserver can encrypt replies. Well suited to peer-to-peer style usage of DNS. Bulk DNS data can be rysnc'd between peers over SSH, or perhaps mrysnc'd among groups of peers.
There is "DNS" as implemented so far and then there is "what's possible" using DNS. Peer to peer sharing of the data is hardly far-fetched. But it does not yet seem to have caught on outside of small groups doing passive monitoring, blocking and other manipulation.
So, on the one hand I see where you're coming from and your comments are totally valid.
On the other hand, there is no actual centralized authority to which one must appeal to to get data into DNS. Want to have porn site blocking? OpenDNS has you covered! [0] Want to attach Namecoin's .bit TLD into your DNS tree? That's available on my LAN and -when last I checked- through a few Internet-accessible DNS servers. Ad/malvertizing blocking for every client attached to your network? Again, just point to (or stand up) a DNS server that's appropriately configured.
In DNS, the "edges" have just as much power as the nodes in the "center", but their sphere of influence is often much smaller.
[0] https://support.opendns.com/entries/46060260-FamilyShield-Ro...
Filtering can be done - certain very-small-scale extensions can be done - and local DNS networks can be done - but if you take the goal of DNS-as-a-global-service as "provide globally unique, globally available name resolution", it very much is centralised.