Rubbish. The German Navy Laws of 1898 and 1900 were clearly designed to take maritime supremacy away from the UK. In the context of a land war against France or Russia the German Navy was irrelevant. It could only threaten the UK. But unlike Germany, the UK needed control of the seas for survival, so the German naval expansion was a "clear and present danger" which drove British foreign policy throughout the early years of the century
The need to concentrate the Fleet in Home Waters drove the alliance with Japan in 1902, the Entante with France in 1905, and Russia in 1907. And the 1912 agreement with France which allowed the Mediteranean Fleet to be moved to Home waters. Once that was in place, Britain was committed to the alliance with France in the event of a German attack.
Germany also conducted an aggressive war against British shipping in 1914. It was only because the German Navy was successfully contained after that that made the naval was "a mere sideshow". That the blockade worked does not mean it was unnecessary.
British fears were unwarranted.
The French Navy was larger than the German at the time of the war. Let alone during the buildup. Germany had practically zero navy in 1870, and even by 30 years later was far inferior to even Russia.
That they would ally with France to protect their naval supremacy is bizarre, they had just spent close to 30 years battling them to reach naval supremacy in the first place.
Germany needed a navy in the Baltic to control the straits and protect their shores.