IP addresses are centralised in some sense but they only really govern inbound connections. as i see it the main point of the relay architecture is exposing the potential for rendezvous points if all else fails.
supposedly ipv6 gives so many addresses that there doesn't need to be an authoritaah about who gets what numbers below the level where the standard issue is 16 bits of address space for anyone for practically peanuts.
moving the goalposts is a primary attack on any system. for IP networking this is addresses. for blockchains it's the agreed current time.