This is an interesting question.
On the one hand, we would like to allow it. Groups are supposed to be helping to do things that wouldn't normally be done on the forums.
On the other hand, it would be difficult to moderate. Yes, groups are moderated by the group owner and group moderators. However, they must still abide by the general site rules. If you introduce software piracy or illegal things, it will be difficult for us to moderate it. We don't currently have anyone who speaks Chinese in the staff... at least not well enough to read it fully without a translation tool.
To mitigate the risks, we could allow to create a private group so that its threads will not be found on Google? But the issue would still remain. What if someone posts child porn in some form without links for moderators to click (like instructions or tutorials
to access illegal sites) and whatnot?
This is an open question at the moment. I suggest we continue debating it here.