Wikipedia find its categories relevant. They certainly provide a great start. Once there were only 13 Eritrean nationals known to Wikidata. Adding thirteen more by hand did not take long. This was done by adding people mentioned on categories like the "Category:Eritrean people stubs".
That was cool. The latest tool by Magnus called Widar makes it even easy to make Wikidata aware of Eritreans. It is just a matter of selecting the right category and making sure that only Eritrean people are selected.
As you can see in the query part of Widar, you have to watch out for the fluff that is endemic in categories; the lists and even a few US ambassadors to Eritrea.
Now that it is possible to populate Wikidata from categories from any and all Wikipedias with "Widar", studying Wikipedia may go to the next level because studying Wikipedia updates Wikidata and it improves the use of Wikipedia in return. With more statements on more items automated disambiguation becomes ever more powerful. With more statements "Reasonator" becomes more informative. With more statements the Wikipedias that include info boxes will be more informative as well.
The one reason why Wikidata might not be used in this way is because the data acquisition changes the subject that is being studied. Then again, as the reflection of the information in Wikipedia improves, the conclusion based on the queries performed on Wikidata will be increasingly informative. Even better, the information will always be near real time and it reflects any and all Wikipedias.