I previously thought groups didn’t exist in Discourse but this thread and this example suggest otherwise.
However, according to this post, only the admin can create and manage them.
@Bart if you find the feature, maybe you could create a “Groups requests” thread where people could ask you to create some groups they want ?
I don’t really get the point of this being only accessible to the admin but I think groups are a useful feature and Discourse provides options that allow them to comply with various requirements.