I don't see how 'hire people who aren't proven' can be compatible with 'can this candidate do the job'. You want to know if they can do the job, but you aren't interested in any proof for that?
That is only true if you see the list of things a person can learn how to do as a closed set. For instance, I really disliked maths in school. I've avoided every software job posting that involved any maths (3D, statistics, etc). However, if I was given a job offer to work on a math-related product I deeply connected with, and that I felt I wanted to contribute, I'd probably be more interested in learning the math st…
If you have to for example build a new operating system kernel, or a new compiler, or implement a machine learning system, hiring a bunch of well-intentioned smart people with the vague idea that they can probably figure it out as they go is a bad idea. You sometimes need someone with a track record of being able to do the work you need done.