[jwbensley]

It does say quite near the start that Jon joined SO in 2008 and further on "In the near decade since then, Jon has answered over 34,000 questions, which works out to about 10 questions per day!" So I don't think he's just doing nothing and getting rep. I'm sure there is a bias, often people have a few good questions or answers that stand out and pull in the majority of their rep, like you mentioned about being idle for circa 1.5 years. However, if you read that post it seems Jon is still actively contributing.