Password managers are great (and I encourage you to use one), but there are instances where the device you are using can’t (or shouldn’t) have one installed and/or have harder input methods (a router, public/shared computer, an IOT device, etc). On these occasions, you shouldn’t sacrifice security. The passwords that this App generates are relatively easy to remember and to type, and are a lot better and safer than the ones a human can come up with. I use the Diceware™ concept, but instead of using a physical dice, I use a cryptographically secure offline random number generator (the one included in your device's OS) to "roll the numbers".