Why is peer-to-peer architecture the simplest form of network?

A P2P network consists of peers. Each node can interact with each. The technology under consideration is based on the principle of decentralization, that is, all nodes in a P2P network are equal. This principle has provided such advantages of P2P technology over the client-server approach as fault tolerance to loss of connection with network nodes, increased copy speed due to copying from several sources at once, the ability to share resources without being tied to specific IP addresses, the huge network capacity as a whole and etc.