The intention was to show that David, as a school kid, couldn’t afford high-end equipment and was using hand-me-down, or second hand equipment.
To most viewers today, that distinction is lost, as it’s all almost equally in the past.
The movie is probably what taught me modems existed however.
Recently I’ve watched it and wondered why he’s using an (expensive but old) 70s style computer rather than a cheap 80s home computer and now I know, thanks.
Or is it just that between writing and releasing technology had changed so quickly?
In a world where every other film is "hacker in a dark room wears a hoodie and cranks up EDM while CSS scrolls on the screen", WarGames appealed to nerds as an exploration of current tech, and a cautionary tale of a possible future.