I believe the main reason someone will start looking online for answers is because the game doesn't give them those answers. If there's some in-game way to look up the exact damage formula, or where to go to advance a quest, or the drop tables of every enemy so they can find a certain item, then as long as said resource is correct and well-built, players will most likely default to using that resource instead of an external one.

You may notice that this directly contravenes the desire of wanting players to "figure it out themselves". But just because the game lists everything out, doesn't mean the player will automatically understand how they all work together, or what the optimal strategy is. And you don't necessarily have to reveal everything immediately, as long as the player's never thinking "I need to know X right now, where is it?". Besides, many casual players will naturally not look anything up (online or otherwise) until they feel stuck.

None of this is going to stop at least three wikis from appearing, of course. Advanced players will always want/need to know more than you ever thought necessary. Speedrunners will want to share tricks and glitches. Devoted fans will want to advertise and analyse the lore to bring in more new players. You could always try the direct route and make a wiki yourself, which would in theory allow you to control its content (and maybe have the game use it directly), but the moment you tell people "no" about documenting something, they're gone to make their own.

Fundamentally, this question is "how do I keep people here instead of going elsewhere?". And the answer to that is almost always: "do what they need better than anywhere else".