She's a DPS Support.
Y'all are always so stuck on ONE roll it's ridiculous. She isn't gonna go out and just do DPS only; not how she's played. Yes, she needs to attack to heal others, however, don't just wander off and leave your team. She's better in a group.
And for the love of anything cute, stop shooting her damaging orb at the enemy team in open areas thinking it's going to help you. It's not. Use it in team fights, use it in small corridors / small enclosed spaces and use your right click to follow someone. It does FAR more damage that way.
The only time you want to use the damage orb in a large group is if they're a) clumped together and b) almost dead. You get more utility this way.
It also does more damage if you directly shoot it into someone.
When in group fights, shoot it towards the healers and squishies first, let your more damaging and tankier players deal with their tanks. Moira absolutely MELTS squishies with a damage orb + right click.