Imagine that you are junior in high school who expects to attend college. At that point in your life you have opinions related to frequent personal choices if blue jeans feel comfortable or if you prefer vanilla to chocolate ice cream. And you have opinions on social norms in your social world, like how much money it is okay to borrow from a friend, how late one should stay at a party, or what are acceptable excuses for breaking up with boy/girlfriend. And you know you will soon need opinions on imminent major life choices, such as what college to attend, what major to have, and whether to live on campus.
But at that point in life you will have less need of opinions on what classes to take as college senior, and where to live then. You know you can wait and learn more before making such decisions. And you have even less need of opinions on borrowing money, staying at parties, or breaking up as a college senior. Social norms on those choices will come from future communities, who may not yet have even decided on such things.