First, not everything is on Nostr.

Second, Nostr notes are not non-repudiable because of the many ways they could get compromised, even with a remote signer (signing some unintended notes before access is revoked)

And you still need a relay to store that note… which will become harder and harder

Personal relays don’t fix this because they are limited to people who know how to run a server, and are intentionally limited to a small group of people. Also, maintenance cost will only go up while the benefit doesn’t change.