The ability to create and to judge might well be separate. How many food critics are good chefs, and vice versa? Perhaps it's due to not having a horse in the race.
What's fascinating is that we have these people who contribute huge amount of content, like the review guy that's mentioned.
Some of these guys are even interactive. I've had programming questions answered by Jon Skeet, and it just boggles the mind how he can be so productive.
There's probably some specific life circumstances that have to come together for us to benefit from a guy like that.