Create Sub Organisation under Partisipant Administration

When busy with some administrative task today i noticed that under  <My Organisation> > Utilities > Participant Administration I have the Option Create Organisation.

When creating such sub organisation(<My Organisation / My Sub Organisation>) and a bit fiddling around with it I noticed the following

• I can add users to it but the Users Domain / Cabinet is still <My Organisation> and not <My organisation / My Sub Organisation>
• I don't see my suborganisation in the Organisations list (Browse > Organisations)
• If a user belongs to <My Organisation / My Sub Organisation>, where is no administrative Level, So the user can only be administrator of <My Organisation>. But then it don’t have andministrative any rights. (no acces to Organisation, can’t create contexts, etc)

So what is the usecase of creating suborganisations?