A print index does not organize all the information about a subject in one location. It doesn’t even organize all the information in your personal book collection about a subject in one location. It organizes all the information in one book about a subject in one location.
We are no longer subject to that constraint.
But the question is: Without any artificial barriers, what information should go with a subject?
Example: Online maps co-locate information about hotels, convenience stores, bars, etc. with physical locations.
That is a tiny number of the subjects that we see or read about in a week. What would you like to see with those subjects?
Exercise: Every day for the next two weeks, take pencil/pen and paper around with you. At least once per day, twice if you can manage it, write down a subject you want to know more about. Without stopping to think about difficulty, expense, etc., jot down 5 pieces of information you would like to see with that subject.
Extra credit: For extra credit, rank in what order you would like to see the additional information.