Guides are useful for those who really have no idea how to play a hero at all. I find that guides for new players should have a cookie-cutter, can't go wrong build that they can go with that should allow the player to get used to the hero.

Leave the discussions on when to deviate from it for when they get used to the hero and can actually think about whether or not an item is apt for the situation or not.

I suppose you can even have an "Advanced" section in guides and have people write down situational items and discuss in length the situations where you can get certain items. Maybe even include when to forgo getting certain items that were included in the cookie cutter build.