Quote from https://37signals.com/26.html,
Usability this, usability that. With all the talk about usability people sometimes forget the other "u" word, usefulness.
You can have the most usable site in the world but if it doesn't provide a useful, helpful service, you're just wasting your visitor's time. And, when your visitors are frustrated, your competitors are their best friends.
So please, be usable and useful."