Employers ask what makes you unique for a number of reasons. They want to know that, beyond your skills that'll get the job done, you'll be able to bring something new to the table and that you'll fit into the company culture. Sure you can do the job, but can you do the job in a way that inspires those around you or that brings new skills to the table to share with others? Will you get along with your teammates and be able to challenge and uplift them? Employers want to know that you're not only a good candidate for the job, but that you're an ideal candidate for the job.