[pbhjpbhj]

You can send email without using DNS.

I'm not sure I'd call IP addresses centralised, if perhaps you were thinking of ICANN's running of IANA?

If you consider the internet inherently "centralised" then surely you'd still find CB radio or similar to be decentralised. Or do you also consider the allocation of wavebands to be "centralised"?

[michaelmior]

Depends on how far you want to push the definition of decentralized. The routing infrastructure of the Internet is still fairly centralized as is the allocation of IP addresses.