Digital media deteriorates too, it can be corrupted subtly or obviously and it can fail catastrophically. Backups and archival especially over the very long term are not simple or straightforward, it’s easy to make mistakes and for accidents to happen and a broken link in the chain can lead to the failure of the whole chain.

“Defense in depth” is a good principle to rely on here. Digitization of physical media media makes sense and the risks are on the whole probably easier to avoid since keeping multitudes of digital copies is logisticially trivial compared to making physical copies. But that doesn’t mean it’s without risks, and may fail against risks that a physical copy wouldn’t. Both is better than either one, and either one is better than none.