Offline backup is really necessary, it is the best way to recover back backup information, it is also the safest from online attackers, that is why it is just the best. Also, many people like stringent ways to backup informations like seed phrase, private key and passwords, which supposed not to be too stringent. Some will even look for their own means of encryption. Stringent ways of backup can lead to loss of such information.
Depending on the format you choose to store your credentials it could still be considered unsafe. Since, if you store it offline, but digitally there's mechnical failure of the hard drive, or there's a damage risk etc. If you store the credentials on a piece of paper, that piece of paper might get lost, or damaged. No matter what format you choose, there will always be some sort of risk to it.
The best policy is looking to reduce those risks as much as possible, and having several safety ropes if things go south. Of course, this takes additional effort, so you rarely see people taking the extra precautions.
Having your crypto storage and codes/words/backups in a safe is great.
Take the extra step and put them in a sealed plastic back inside a fireproof bag inside that safe.