Yeah, a cleric can tank and multitask, but they will never be a better DD than other classes. It's not how the class is built. If you can tank and heal at the same time, do so xD Any cleric can DD and still be counted for a good DD as long as they are not compared to other classes. Because in the end, a cleric isn't a damage class at all.
There's a reason people ask clerics to heal, buff, rez, and stuff like that. Because naturally, they're better doing that than anything else o: