Games had to be smaller projects. The console and home computer hardware at that time put a tight limit on how much code and data you could ship. Filling that up wasn't hard. It was mostly a matter using these resources well.

This changed a few years later when CDs came along. Many game devs originally didn't quite know what to do with so much storage space. Then processors also got much faster still and 3D acceleration became a thing. Game dev project scopes exploded accordingly to give you the game industry we have today.