Any guarantee made by manufacturer about data on tape longevity is irrelevant unless it is easy for user to create the storage conditions under which is warranted, and that is usually not cheap.

not hard to find stories about data on LTO tapes being unreadable after 5 years. The same as stories of data on even the worst CD-Rs being still readable after 30 years ( i can personaly attest to that).

Some CD-Rs will certainly be readable after 30 years, but there have been plenty of bad CD-Rs that have become unreadable after less than 10 years.

I had several hundred CD-Rs. Most of them were OK, especially the gold archival CD-Rs from Kodak, so I have migrated the data from them mostly to save space and improve access speed, not for them being too old. Nevertheless there have been a few that have gone bad, but I had duplicates for all of them, so I did not lose the data. Had I not been cautious, I would have lost some of the data.

The main problem of optical discs is their much too low capacity in comparison with magnetic media. A small suitcase with tape cartridges contains as much data as a big cabinet full of the most dense optical discs.