Not all places do this; the place I currently work only rewards leaders for "impact" and people have the option of whether to take on leadership responsibilities.
Places that reward non-leaders for impact are doing so intentionally to encourage people to self-organize into teams that produce the most value for the business. The theory being that the people on the ground often have a clearer view of whether value is being created than the various layers of middle management do. If you work in a place like this it's actually part of your job to stay plugged in to the business side and determine whether you're working on something valuable or not.
Places that reward non-leaders for impact are doing so intentionally to encourage people to self-organize into teams that produce the most value for the business. The theory being that the people on the ground often have a clearer view of whether value is being created than the various layers of middle management do. If you work in a place like this it's actually part of your job to stay plugged in to the business side and determine whether you're working on something valuable or not.