Seed phrases are prone to human error. We want to mitigate any possible points of weakness in security and this doesn't just mean something a hacker could exploit.
A seed phrase is recommended to be written down on paper and kept somewhere safe. But what if you lose that piece of paper? What if you have a fire? What if your house gets robbed or your partner throws it away while cleaning?
There goes your recovery option! Human error is the biggest security flaw in history and this stress is not what you should have to deal with when maintaining your crypto.