I see what you're saying. I think mystery is a byproduct and not so much a goal. Sometimes you set the stage for it and it happens and other times it doesn't. Sometimes you don't plan for a mystery and the things fall into place to make it so. I don't think it's worth worrying about, and when DMs do worry about it, they run the risk of becoming inconsistent in their adjudication as they push for particular outcomes.
Totally agree. But what I don't want (to link to the other thread) is for a player to say, "Can I roll Insight?" and spoil the fun with a die roll. That's not solving puzzles; that's rolling dice.