Large light cruisers and Incomparable were not Royal Navy endpoints

Should the large light cruisers and HMS Incomparable be treated as the logical endpoint of British battlecruiser design?

No; Incomparable was Fisher's personal concept, while official British design work continued along other lines.

These concepts do not form a logical endpoint for British battlecruisers. The large light cruiser line did not end naval design work, while Incomparable was a personal Jacky Fisher proposal. It was an exploratory concept from a retired admiral seeking renewed influence, not a design being developed by the Director of Naval Construction. The distinction matters because spectacular paper ships can obscure the institutional design work that a navy was actually prepared to build.