I share your concerns. I've been chatting with a few people about this and made various false starts... It might not be my project, but I felt I could write down the risks I saw in how the wiki is ran: https://nixos.wiki/wiki/User:Winny/WikiRisks (including vulnerable server software)
The next big problem with NixOS documentation is that there are a lot of smaller tutorials scattered around the web. Every page with a different style, focus, and depth.
What we need is one central wiki, where any problem search can begin.
This is what makes the Arch wiki so great.
Because forking is also expensive and people would need to discover the new domain. Otherwise I would already have done it. We already have the issue of having too many different sources of documentation. And hacking the wiki is the last thing I want to do... I don't want get visits from the police from $someone.