Seriously, though, Tobar explained the idea in two sentences. Surely it can’t be that hard for the writers to do likewise?
Maybe not but why if there’s no purpose or need?
Proposed EpVIII scene
Rey is doing a handstand with Luke sitting on her foot
Luke: Concentrate
Rey: But Luke, how did Artoo have the map?
Luke: Why is that important?
Rey: Because I need to EXACTLY how I was able to find you.
Luke: But… you’re here now.
Rey: Tell me I need to know or it will bother me forever and I’ll never stop complaining about it.
Luke sits down on a log and Rey joins
Luke: Well, as you know, I put himself into a self-imposed exile. If anyone ever needed me, I trusted Lor San Tekka and Artoo to know when and if to disclose my location. Separating the map ensured that it meant both of them agreed that I was really needed.
Rey: Thank you for taking the time out of my training to explain this! Plot hole resolved!
Seriously though, they could easily explain this more efficiently in the film, but I see no reason unless something else (not easily inferred from watching TFA) in addition is revealed that pertains to more directly to the plot of VIII (not VII).