Using one of the most exceptional, one-of-a-kind fighters as your example doesn't make the best case.
"Dana shilled hard for him," is a really bizarre statement. Dana is the president of the UFC. Silva was the champion of the UFC's MW division with a long career and a huge fanbase. Since when is a president of a business (the business of fight promotion no less) promoting the promotion's reigning and popular MW champion shilling? Do you know what a shill is? Dana is not a shill, and could never be a shill so long as he remains president of the UFC by definition. Like, what did you really expect? Dana to not promote AS?
Anyway, why shouldn't Zuffa promote whoever they want to promote? Zuffa, as a business, is going to do what is in their business interest. Promoting their products (fighters/fights) is in their business interest. Water is wet, the sky is blue.
Let the fighters fight however frequently they want, and let them compete with each other as much outside the octagon as a product just as they do inside the octagon as a fighter.