I'm interesting in knowing IBMs thought process around the design of teams and subteams in RTC 2.0

For various reasons, one may not want to make all teams public. One would think that if I have a team with sub-teams underneath it, team members of the parent team should be able to file against a subteam.

However it appears this is not the case. I have to make each member of the parent team who may need to assign work items to a subteam a member of each subteam.

Is this a design flaw, or is there a use case I am not understanding?