For a wiki to be truly useful, the wiki Permissions need to be adjusted in the settings by the OWNER to allow it to be editable by members,
If there is one thing I've learned using wiki's for 10 years, getting people to actually contribute to a wiki is the challenge.
I have NEVER had anyone so rude to actually sabotage the project.
Most people who use them are passive but appreciative. 

I believe the most useful setting to be:

Public can view, Members can view and edit

The wiki permission settings are documented in Help Center > Owners Manual > Customizing group settings > Settings for Premium and Enterprise features.