1. Decentralization won in 1970 - 2005 protocol design because reliable computers were very expensive. It was economically advantageous to have a decentralized network of unreliable computers than centralized unreliable protocols. Reliable compute has now become commoditized by the cloud services. This creates a pressure for centralization.
2. Decentralized protocols have not aged well(TCP/IP, SMTP), have deep security flaws and have proven difficult to upgrade. This has created new centralization pressures to cope with the security flaws(Gmail, Cloudflare)
3. There continue to be pressures for decentralization related to both politics and security pressures. Tor and blockchain cryptocurrencies are excellent examples of these. But decentralization is unlikely to extend all the way to edge devices and instead operate in a federated fashion.