MoinMoin can be used for Collaborative_writing. This starts from simple todo lists but can also be used for real complex texts like documentation. MoinMaster is a good example how this can be organized. You either choose to use to have write access to a wiki (or subproject inside the wiki) only for a special group (then you need HelpOnAccessControlLists) or open to everybody (like the Wikipedia). You also can mix openness and closeness in the way that you protect some pages from allowing everybody to edit them. So you can do apply very fine grained rules to your pages.
It is generally a good idea to allow more people to edit content and to only protect where absolutely necessary. It is often better to apply more rigid rules if bad things really happen. This is because excluding anonymous users makes contribution more complicated and they will not contribute at all more likely. Often anonymous contributors can provide valuable data or activity. They might even choose to register themselves when they get comfortable with the system.
Also do think about applying default licenses to every added content. This makes it easier to share. Some good licenses for sharing are the GFDL and the Creative Commons Licenses. To apply them automatically you will have to configure your wiki with page_license_enabled, page_license_page and maybe also a page footer ( see HelpOnConfiguration).