Yeah, as a healer in Fates, I have to say this. I will heal non-party members if I can with ease.

If you are running around like you have a hot coal in your underwear, or way out of range, or I can't see your name b/c there's 20 other people in the same area, then sorry too bad. If the Fates are difficult enough to need healing, then ask us to join your party. Problem solved.