It seems like the original research does mention this problem.
"At the same time, we see a puzzling fact that Baidu is also listed as the most visited website in South Korea (ahead of the popular South Korean search engine, Naver). We speculate that the raw data that we are using here are skewed."
"At the same time, we see a puzzling fact that Baidu is also listed as the most visited website in South Korea (ahead of the popular South Korean search engine, Naver). We speculate that the raw data that we are using here are skewed."
http://geography.oii.ox.ac.uk/2013/09/age-of-internet-empire...