If you follow the rather important good practice of having a unique password for every account. You will immediately be challenged by the sheer number of different credentials that will be needed to authenticate with all these accounts. With these many hundreds of credentials (passwords etc...) you wind up with in our modern lives, password vaults/managers are effectively an essential. They also provide a host of other useful features. In fact, once you get used to having one it will usually save you so much time, you'll wonder how you ever lived without one.