> There are ways to store data securely, one of the simplest methods is to do zero-knowledge encryption of that data by way of key-generation from a password only the user knows at the time of decryption.

This keeps your passwords save until you enter your master password. At that point you have to trust the software that was downloaded a few days ago from an appstore or a few seconds ago from the company webserver. It might have been backdoored and happily phone home your master password.

Your downloaded password manager might be a few years old and YOU decide when to upgrade.