This is key, many companies gimp there documentation process with too much access control. Recently for instance, I wanted to update the company leave policy page with a link to the application form but couldn't because it was locked to HR.
I'm not that familiar with the auth situation for your wiki of choice, but "no registered users" isnt the only solution to "too much access control".
Having people authenticate as themselves, but still allowing global write to the wiki for all users gives you an electronic paper trail of who modified what.
Another solution might also just be "the right amount of access control". Maybe there's a good reason only your HR department can edit the leave policy page, and you could/should have asked HR to update the page, or asked for access to edit it yourself.
