What security benefits are gained from having a password manager, versus having the passwords stored in plaintext on an encrypted volume?
Both would allow one "master" password, both would (potentially) allow external storage of encrypted data... what would be the benefit, from a security standpoint?
Of course, usability is not unrelated to security, so if there is a point to be made with usability it may relate to this as well.
This is not asking about a specific product (such as KeePass vs. OneNote), but instead is focused on a higer-level comparison of methods available to users of most modern OSes.