The UFC does a good job of promoting its stars because, unlike some organizations in our sport, they seem to understand that they need to ride those stars as hard as they can. Of course, there are limits you want to see organizations have to make sure it is still fair competition and not just something like WWE (see NBA).
The accusations swirling is that surging megastar, Conor McGregor, received help from the best wrestler on the planet, Jordan Burroughs, before UFC 196. While seeking help is not a crime, most people seem to point to Dana White as the one who put the two together. This alleged preferential treatment seems to have ruffled some feathers.
You can read about it here