This kind of bug is pretty much the point we're using seed phrases, and the holders who lost their coins this way could still have access if they had a seed phrase written down.
People who lost their bitcoins due to this bug should've kept a digital backup of their wallet file
since keeping a backup of your wallet is a no-brainer, with or without a seed phrase.
But I get that some non-tech-savvy people will definitely skip it.
In comparison, it's mostly mandatory to save the seed phrase when creating a BIP39-compliant wallet.
While in Bitcoin Core, the client wont tell you to save a backup when creating a new wallet (
aside from when you encrypt an unencrypted wallet)
