The difficulty helped hide the fact that you were paying $50 in 1980s money for a game that took approximately an hour to beat. If you could beat it. But I suspect the more common gameplay loop was the one I and my friends encountered: you put the game in, played for 20-35 minutes, got a Game Over. If you were really motivated maybe you tried again and got to Stage 4 instead of Stage 3, but at some point said, screw it, turned the game off, and played something else.

These days every game is made with the intention that it can and should be beaten, which is part of why there's so much needless padding in games to stretch them out beyond the 40-hour mark and make the player feel like they're getting "value" for their money.