capability is what a thing can do. purpose is what a thing does. if the wrench sits in a drawer and rusts, if it turns nuts, if it gets buried under the foundation of a workshop for good luck, melted down for the materials; regardless if it gets used in a manner other than its creator's intention or not, the thing it does is the thing it was meant to do. destined, if you like.

people are always wondering what the 'purpose' of their lives are, but that can only be known in retrospect. what did you do with your life? that was its purpose. so too with a wrench or a rentabike or any other thing.

https://en.wikipedia.org/wiki/The_purpose_of_a_system_is_what_it_does