The EPQ is for students that possess a natural intellectual curiosity - they are not simply academic and great at passing exams, these are the students that actively seek out opportunities to further their learning in their interest areas.
For students who want to apply to a course that you cannot study at A Level - medicine, engineering, architecture, dentistry - the EPQ gives them an opportunity to showcase their interest.
This is for students who already know what they would like to study and the project allows them to identify a particularly relevant, cutting edge or controversial topic in that area as a point of differentiation.