What does it mean that the graph outlives any single organizing system?

Example: Niklas Luhmann's Zettelkasten — 90,000 paper slips linked by a numbering system he invented in the early 1950s — survived his death in 1998, was purchased by the University of Bielefeld, digitized, and published online in 2019. The slips were written in a format any literate person can read: handwritten German on index cards. The linking system — branching alphanumeric IDs like 21/3a1p5c4fB — required no software, no database, no proprietary viewer. Sixty-seven years after the first card was filed, the entire graph was migrated to a digital medium without losing a single connection. The tool changed. The graph persisted.

Try this: Open your current knowledge system — Obsidian vault, Notion workspace, Roam database, Apple Notes, whatever you use. Export ten connected notes. Now open the export in a plain text editor. Ask: Can I read the content? Can I see the links? Can I reconstruct the graph from these files alone, with no special software? If the answer to any question is no, you have identified a portability risk. Write down what would need to change for your answer to be yes.