Like, think about some well-known SaaS and IaaS providers, think about how their services might be implemented in a decentralized manner, and on what point that might become difficult - and most of the time, the answer to that will be "namespace management", that is often really the only part that benefits from centralization in any serious way
(The cryptocurrency folks actually identified this problem correctly, even if their proposed solution was completely absurd and unsustainable...)