It is actually pretty difficult to do. That's why it is not more common.
Once you learn how to do it, it gets easier. But there is a steep learning curve. Most start up tournaments are total disasters. And by the time the promoters have learned enough to fix their mistakes, the brand of the tournament is usually already ruined from the previous failures.
What are some of the challenges?
I'm not experienced with tournaments (about 4 in 5 years).
I'd imagine a big challenge would be finding refs. I'm asking from the perspective of a gym that wants to start a small tournament in their own space and not as an independent person looking to build a brand.
Another challenge I'd imagine is maybe dealing with the sheer size of the pool of competitors and arranging brackets? I've had friends successfully organize basketball tournaments with 100+ people, but the teams that make up brackets are much smaller than brackets filled with individual competitors.
Anyway, sucks that GQ is going out of business. I considered them a "household" name around here.