They have that event at "Equine Affaire" (at least the one in New England) each year. I participated a few years back and it was a great experience. They called it a "versatility" competition. Several videos on YouTube of various competitors.
This is something that seems to be growing. A local barn here has started their own.
One of the keys to get this going is to organize practices. Get interested people together, set up various obstacles and let them try. As you build of base of "regulars" it becomes easier to organize competitions and events.
Many places get sponsors and have added money, which always draws more people.
The toughest thing to set up in this is the judging. Each obstacle needs a judge to evaluate performance (if working in an arena or small space, one judge can do it all). Frankly, I never understood the workings of this subjective element which comprises the majority of the score.