This style of client and server application has its roots in things like `inetd` (internet daemon) and CGI (common gateway interface). Benno Rice explains in a section of his excellent presentation covering the history of linux and unix:

https://video.strongthany.cc/watch?v=o_AIw9bGogo&t=4m58s

> [Then things changed...] the internet happened. That inetd model was great when [you were dealing with a small amount of stuff going on], like, [only a few users would have telnet connections] ...The web looked like it would work that way too, and then it became really really popular. And so you end up with situations where forking off a process to handle every single connection doesn't really scale that well.