It’s not that. In fact you can go read my thread with suggested changes here:
What I want to tell you but you can appearently see it is that.
Bringing people with less than 100% with res is a bad idea. Why? Because mercy will just pop out and heal the targets and get near 80% towards another res (if a teamfight breaks out she maybe be even able to get another res within 30 sec of the first one thanks to your AoE heals on valk. If ressurect has resource like ults do, targets should respawn with less than 100% as mercy can charge ult again off them