One of the major points levied at Volcarona during its suspect was that it was rarely a dead slot. Even if it wasn't 6-0ing teams on preview, its typing and abilities allowed it to stay relevant and still contribute. I feel much the same about Roaring Moon, the only major differentiating factors being that it's mostly limited to HO teams and you don't have to contend with a bucketload of shitty RNG. Even in the games where it doesn't look like it does much, its ability to force progress often lets you later end up in a winning position.
I will say that I'm definitely not convinced yet that moon is banworthy, and the current meta is quite good for it. We'll have to see as the metagame adjusts, but I've played enough recently to feel that it's definitely an unhealthy presence in a lot of ways. You know exactly what set it's running and it still rarely ever fails to do its job.