I think it may just be more obvious in golf. When a professional golfer's swing seems dramatically different and the result is bad (ie, the obvious deceleration of Watson's putter on 18), then what's left to say, but that he failed to execute the shot? There are obvious chokes in other sports (Buckner's muff in the 1986 WS comes to mind), but in golf they are more easily noticed. Additionally, if you define a "choke" as a mental breakdown, then high pressure golf just seems like the perfect storm for such a situation.