Mercy from Overwatch is a perfect example of why pure healers don’t work too well in shooters. She is consistently throughout the games lifespan either been too overtuned or too undertuned. It is very difficult to find that balanced spot for pure healers.

They either end up too powerful and require constant tagging by the opponents team which is frustrating both for the healer player and the opponent team. Or they become almost mandatory for a team too win even in a casual setting, which is incredibly unfun for both teams.

In the case of being undertuned though, if they’re not powerful enough then no one picks them as it is just not as fun or engaging to play as a pure healer.

Or finally in the case of medic from tf2. They become a fairly predictable 1 trick pony, low reward class.

Overall pure healers in shooters just really don’t work well for the medium/genre. I love being a support player myself in games. But I loathe seeing pure healers in shooters. It’s nearly always just a source of frustration rather than fun