Can a management company be fired by the board? Then it is a contractor. If the management company can fire the board. Then it is part of the management of the HOA.
The HOA sub-contracts a MC to handle it's issues they want the MC to handle CONTRACTUALLY. Hence why the true relationship of a HOA and a MC Contractor and sub-contractor.
Rule of thumb: If you can fire it, then it's a sub-contractor. If you have to be hired by it, they are the contractor.
There's nothing wrong with this relationship with the HOA and MC. It's just a business setup. Many in a HOA confuse the true MC's relationship. They depend on it so much that they don't know any other way. Surprisingly, most HOA's are setup to be self managed amongst the homeowner's entirely. It's just easier to hire a MC who's willing to manage on the owner's behalf instead. Smart business sense if you ask me.

It doesn't mean the owner's have lost complete control. They just decided simply to hire out the services instead to an outside source. Just like this poster is considering.