It's incredible how much stuff you can churn out when a lot of work is done by volunteers and not only paid staff.
Also, as a volunteer, you have a lot of freedom in starting projects inside the main one, there's a real sense of meritocracy (you are valued for the work you do). I, for example, have been the topic leader for the MDN Glossary, a sub-section of the learning area.
I recommend volunteering on MDN to anyone who wants to start technical writing and needs some guidance.