While everyone is not necessarily a great writer in all aspects, they usually know what they do well. Someone may be great at organizing but not be a good proofreader. Someone else might be great a vivid language, but lose their focus. Have group members write what they're best at and/or ask them to read the first draft for specific things they know well. Even if you're good at all aspects, this doesn't mean you can't draw on the others' strengths.
Back to I'll end up doing all the work...