What should actually go on-chain?

It's easy to reach for a chain because it sounds trustworthy. But a database you control is faster, cheaper, and simpler — until you need strangers to agree on state without trusting you.

A simple test

If you are the only one who could ever dispute the record, you don't need a chain.

Put on-chain only what must be censorship-resistant or independently verifiable: ownership, commitments, provenance. Keep everything else off-chain and reference it by hash. That split is where most sensible designs actually land.