It is posisible that the strategic design accountability will be more effective when more distributed. Even without a single person concerned for the whole. Surely there is still some other person or group who is concerned for the whole. The possible advantage arises from the condition of the space of possibility being too large to fully explore and too complex to evaluate optimimums. That means, that any single choice can easily get stuck in an apparently good strategy which is merely a local peak which is also fairly low compared to others not discovered.
Distribution can support the exploration of more of the space of possibility.
The other design consideration is that strategy be a matter of the intelligence, awareness, thinking of the total organisation and that the strategic leaders are accountable for gathering, interpreting and providing feedback to the organisation about strategy rather than taking an expert position on somehow independently deciding strategy. If the expert position is being taken, then the split will still have the added exploration possibility but miss the largest potential. If the position is one related to the distributed intelligence of the organisation, then the dangers are minimal and the design may even be optimal. The concerns we have are generally founded in unexamined bureacratic, hierarchical and linear views of how organisations work.