When I first started working on games professionally in the early nineties, the role of designer was being instituted throughout the industry. Following the mold of prominent designers such as Shigeru Miyamoto and Sid Meier, designers were seen as directors of the game, or at least the people who came up with many of the ideas. The role required communication with the team on a daily basis but not much written documentation.
As technical complexity, team size, and project durations grew, the role of the designer became more delineated. Some projects had teams of designers who specialized in writing stories, scripting, tuning characters, or creating audio. Hierarchies emerged to include lead, senior, associate, or assistant ...