They said IE was the best browser, not the most popular. I wouldn't dispute that IE was more commonly used at the time.
Just checked your link and this fits with what I thought in terms of marketshare. You can see that Firefox was ~25% of marketshare in 2009. Which is an enormous share of the pie when you consider that they couldn't stick a download link on the front page of the most dominant search engine, and it didn't come preinstalled.
Never used Maxthon.
Damn, this also reminded me that RSS feeds were everywhere back then, and the browser supported it directly.