In essence, what you are saying is true---these are pretty close to being hypothetical weapons at this point.
The US has test fired, and intercepted, a few test dummy missiles, and the Chinese have fired their missiles and struck some non-moving ground targets. Neither of these events is proof positive as to how either weapon will perform in real life circumstances. So, what you say is absolutely true.
That being said, we do know that the missiles really do exist. There are missiles that are referred to by these names. How will they perform is anyone's guess. In fact, how will ANY weapon in CMO actually perform when the time comes? Will the Sidewinder still be any good? Will the Sparrow continue to be bad? Can the US actually shoot down these super-sonic, low altitude Anti-Ship missiles? Who knows? Everything is merely a guess at this point.
But, just because it's a guess doesn't mean that it shouldn't, somehow, find its way into our game. I don't see how a current scenario involving China in the South China Sea could be completed without having missiles such as the DF-21 being a part of it. It is what people want to see.
So, whether it's a guess, or hardcore facts, it doesn't really matter. When the Pentagon sits down to play their war games, whether they are using CMO or some other sim, someone there is going to do the same thing that we are going to do---they are going to fire the missiles at the aircraft carrier and see if it can survive. Without a doubt, that's what's going to happen. So, even if it isn't real and everything is boiled down to just guesses, the issue has to be addressed. The topic is too hot.
If we woke up tomorrow morning and heard that the Chinese had fired 8 DF-21 missiles at a carrier group, each of us would be setting up our own scenarios using the same units that were reportedly involved. Why? Because that's what we do. We do this for fun, and CMO allows us to create a fantasy world that we like to believe is sort of/kind of/maybe real. Plus, it's fun.
So, I can foresee that sometime in the not too distant future, the DF-21 (or some other missile) will be fired at real ships (possibly a carrier) and all of our make-believe scenarios will suddenly become very real. Will we (and the sim) be ready?