Not every article is written from a globalist perspective. Clearly 'pirates' would mean something different for so many regions and parts of history. The Med. was full of pirates for quite some time before and after antiquity, surely there were famous names as well.
I suggest that in English, the most popular application of 'Pirate' would be those European Ships in the New World in the lat 1600's early 1700's before the British forced some 'order'.
If the author is intent to talk about Pirates in the context of that well-known era, they're probably not inclined to worry that much about 'Google Searches', they're talking about famous individuals from that epoch.
Im curious by what metric is most famous using? Is it a matter of geography, culture, race, gender, skill, appearances on google searches circa 1999?