Okay, I have a theory for which I would really like your opinion. In Nancy Drew: Ransom of the Seven Ships, there are only four actual characters that you can talk to. There is George, Lulu the parrot, Johnny Rolle the beach bum, and Bess who you find at the end of the game. There are also no phone contacts in this game either.
Now in the Nancy Drew series, the culprit is always someone who you can actually see and talk to. Obviously the kidnapper wasn’t George, Lulu couldn’t have done it, and of course Bess didn’t kidnap herself. So the conclusion is that the culprit is the beach bum because there is no one else in the game!
At some point Johnny tells you that there are other people on the island, but that is of course a lie! My point here is that it is possible to figure out who the culprit is within the first few minutes of playing the game! Please let me know if I’m making sense.
You're making perfect sense, and other people have complained about it. Obviously, the only suspect in the one-suspect mystery is the one who ends up being the culprit. I suppose the REAL mystery is figuring out Johnny's true identity.