One might consider benefit of accountability being perhaps sole accountability in a new role within anchor circle, as apposed to needing to be "part of" an existing role. The reason why I say this is that it might be worthy to protect accountabilities naturally flowing from the purpose, for clarity in the organization.
The purpose for which the new accountability needs to be addressed, is probably something that can be identified (felt) by GCC, so that purpose can be written in the role. The purpose for the new accountability being identified here could be something previously underestimated/not understood by the company, and might be something worthy of much more focus. Having accountability set in this way perhaps allows clarity for additional resources to address this need, which might be more difficult to understand if it's buried in a role that doesn't identify the purpose or modification for the new accountability. Something to consider!