Building an Internet of Things project often relies on the well-established client-server architecture at scale. When the term was first used, it referred to users as the client, requesting to run jobs from a central computer, i.e. the server.  Nowadays, with IoT, clients are the edge devices requesting data to be stored/processed by a server. Although, in theory, a single server could handle a small batch of IoT devices, a sudden surge of device requests could easily overwhelm the server and affect availability and data integrity.
This is where distributed computing coupled with a microservice architecture comes in.