Ok, but that applies to all data on public, free servers (urguably excluding internet archive, other than that they potentially go bankrupt due to lawsuits), so has nothing to with Nostr;
Actually, due to the interoperable/interchangeable nature of relays, would Nostr not improve matters of data availability, if something like say internet archive would be a relay? (As well as self hosted, peer hosted or the already mentioned commercially hosted stuff).