Groups are a powerful tool to push masive tasks and thus productivity, but they aren't much stable as they interact with sorrounding elements, and tend to break or duplicate themselves. This usally happens due to walls' stickyness, so if you want to avoid these issues you can disallow their joining status. This is a simple solution, good for simple cases, but not enough when you want to grow your groups.
This power could be greatly improved if there was a way to freeze groups, whether by type or instance