I read something years ago that those games were designed to have illogical puzzles so that you'd pay to call the help line (yes, there was a phone number you'd call for help) or sell paper game guides

In particular, ‘Maniac Mansion’ has pathways for the characters to die or the player to be stuck without a recourse — which later adventures avoided, allowing successful completion from any point in the game.

I recently tried playing through it for the first time (on an Android tablet with ScummVM), and pretty sure I hit such a dead end.