A while ago I posted my dedicated healer build ( https://www.grimtools.com/calc/YNnxGlyV ). It has no damage, but incredible healing, damage mitigation, and buffing/support capacity for your team (including massive OA/DA buffs (about 420 OA plus 8%), +32% Phys resist etc etc)
Now I have a video demonstrating it’s survivability, and it’s ability to keep even my doctor birb pets alive while facetanking 154 Crucible. Pity I couldn’t do enough damage to get past their regen, but as you can see, neither could they for me. 
I had no crucible buffs or banners to help me, this is just what the character can bring to the table