Client-Server model is expensive, complex, and prone to failure & attack
Today most of the communication need to go through a centralized server, where it can be blocked or sabotaged, hacked into, or eavesdropped on.
Inefficient Network utilization results in waste of resource
Current Internet were designed for peak traffic but most of the time these networks are underutilized, leaving unused bandwidth wasted every second.
Centralization of blockchain systems diminish trust
Recently there are major blockchain projects using a handful of centralized servers to carry out consensus in the name of increasing transaction speed. This sacrifices trust and security, and diminished the technical and economic strength of a true permissionless blockchain system.