[mikebridgman]

One thing to consider is that their target audience is attendees of the Front-trends conference, a conference specifically for front end developers. I think it's a safe bet that a majority of the traffic will have a compatible browser.

[dave_sullivan]

Ha, excellent point. Judging by some of the comments here, much of their traffic may not have a compatible browser version after all, but I'd imagine that they still have a higher tolerance for that sort of thing in the name of advancing the field.