Why would you normally expect the most exclusive implication over the most inclusive when no other qualifying statements were given? The article title mentioned one branded camera and said it outsold all flagships. From only the words in title, where are you limiting the context to only Nikon products?

If someone said "Pepsi sodas are bad compared to all sodas" you're saying it would be normal to assume they're only referring and comparing to other Pepsico branded drinks?