Arrow Electronics Frontend Engineer interview questions

The interview process started with a Skype call with an engineer, a designer and a product manager. During the call they asked about my experience and some technical questions regarding Angular. After the call, a coding exercise in Angular was assigned. I completed the assignment according the instructions. I was declined, according to the recruiter, because there was some weak parts of my code. If Arrow Electronics wanted me to use specific aspects of Angular then they should have stated that in the instructions. Being rejected without an explanation even though I completed the exercise shows the interview process is lacking.