Wouldn't it be safer to have your keys in a wallet.dat of the old format where each key had it's own private key and they were not related to a single point of failure (the seed that spawns all of these) compared to the common "type your 12 word seed to spawn your entire wallet history" wallets? Because if you've got someone's public keys, couldn't you use those to try to derivate the master private key? The old wallet.dat that that was annoying to some because you would need to do backups as it wouldn't generate infinite receiving keys, wouldn't it be safer since each private key had it's own separate public key? Then they changed this and basically wallet.dat also uses this seed system but the seed is hidden and not offered to be safed in the form of human readable words to the user. I've read this is safer (not sure if technically, or simply because there is no risk of screwing up during this process) but nonetheless, there is a main xprv involved, whereas with the old format, there was no main key, correct this if im wrong and let's explore what would the first casualties be in a successful QC exploit.