I think people might keep posting, but instead of copy-pasting the same answer into each post, it might be better to direct new players to the place where they can find the answer to this and other frequently asked questions, i.e. answer with
Please read comments in the pinned post
https://community.wayfarer.nianticlabs.com/t/why-hasnt-my-approved-poi-shown-up-in-my-game-yet
(and add more comments there explaining s2 cells and such)