It won’t give her any substantial ult charge. The point is, they are temporarily down a healer, allowing their team to be more aggressive. Trading a DPS for a main healer is going to give the DPS team an advantage.
No, the trade off for really good heals in overwatch is balancing it with damage. The trade-off for damage in paladins is healing. Understanding which one is the more valuable one is what will tell you what their kit leans towards. It’s like saying genji is a bad hero because low ranked players can’t use him properly.