The OP is pretty much right; which unfortunately means many old adventure games really suck a lot more than people realize.
King's Quest 1-6? If they were arcade games where you put in a quarter for each death, Sierra would be on a higher plane than Activision right now.
The Dig? Old classic, but since it's an alien planet what the heck do you have to base all your puzzle-assumptions off of?
So many adventure games depend on former knowledge or just plain guesswork. It's ridiculous.
Conversely, I will say that I absolutely DESPISE games that constantly remind, or just tell, you what to do. Take GTA4.
"Pick up the C4."
"Fight your way to the inside of the bank."
"Walk into the yellow light to plant the C4."
(cutscene)
"Kill the cops"
"Find a car" (massive arrow appears over the car)
"Hide from the cops" (massive arrow appears over a covert barn)
That's just following instructions. You don't quite feel like you pulled off a heist and outsmarted anyone. It wasn't your idea; it was the game's. And you're just lucky enough to have been pulled along for its ride.
What's better is simply implying the correct path while giving more obvious, believable, in-game hints to what exactly you should do.
"Get away clean with the bank's money"
You walk in. A businessman is commenting to another how he doesn't think his money is secure here; how only the safe door itself is protected, and any wall on the sides could be blown apart easily. You go there, blow up the wall, and the doors behind you lock down, whereas a nearby hole offers a way out. You kill some police in your way before finding a shiny red car under a streetlamp. *score*! While being chased, you constantly hear anything from the police about their line of sight with you being broken, seeing you on a certain street, etc. When you go in a tunnel, they say "I lost him!" By following the cues, you find a secluded spot off the road to hide.
That way, it's the player's ideas and decisions, even though they're really not.