It can only accept a certain amount of information within the line before the signal becomes muddled with other signals to the point that no one can understand what was being transmitted. Each time the communication line reaches a connection point, a switch is used to direct the signal to the intended reception location. These switches have capacity limits too. People can only handle a certain amount of information and requests with efficiency at any one time. That is why we train in specialization's.
Same thing happens for servers and communication lines.
Optimally, a specific server is dedicated to specific type of task that suits its design. When a request come in, the request is routed to a server that is less busy than the others. In others, some servers specialize in receiving information, others in computing it, and still others in transmitting the result. Internet Service Provider. They give you software and a phone number to connect to their communication and server system.