I believe you may be missing the point of the ability to overallocate a resource. By allowing the overallocation, you are then able to compare allocations across resources within a team/pool/role and then resolve the over/underallocations to balance the workload. This may result in continued overallocation, which provides resource managers the data needed to make decisions about which work happens when and/or the addition of more resources to the team.
This is even easier to see and resolve in CA PPM 15.2 in the new user interface for Resource Management. You can see some of this in my blog post on the topic: https://communities.ca.com/community/ca-ppm/blog/2017/03/10/ppm-insights-first-look-at-ca-ppm-152-s-resource-management.
If you would like a more in depth demo of the functionality, please contact your account team.