Why an Italian-Austro-Hungarian naval alliance would not easily defeat France

Could Italy and Austria-Hungary have defeated France if they fought together in the First World War?

Their fleets could probably defeat the French navy, but British reinforcement, difficult terrain, and coalition politics make a decisive victory over France unlikely.

An Italian-Austro-Hungarian naval alliance could probably defeat the French fleet in this counterfactual. Britain would be unlikely to delay reinforcing Gibraltar for long. Success at sea would still leave an attack on France through the mountains. Italy would be unlikely to let Austro-Hungarian troops cross its territory, leaving Italian forces to undertake that campaign under generals judged poorly suited to it.