Do you trust your users to write your documentation? The answer is, probably not. It is not unknown for software developers to fear that their users become, at times, stressed and angry with their software. This can lead to a more difficult relationship between you and your customer, with clients who decide to walk away.
Do you have users that know the software inside out? Would you trust them to write some of your user documentation? What would the benefit be? What can we all learn from Wikipedia? If others do this, where will that leave you?
I would love our users to write about how they use the products. In fact the product is so customisable I’m sure they already do write their own procedures for each area of use. I would love to see this so it could be incorporated into a database of procedures and re-used by us elsewhere for similar users in other companies. It would save us a heap of work and make us able to provide more to more people in the long run.