Oooh oooh oooh, I wanna make an anology too, this is fun.
We are a squad of marines on the front lines. We have a squad leader, several people in a firesquad and a marine medic. The medic is there in case of injury and to treat the wounded, but if he refuses to pick up his rifle in the meantime, he'll be booted out of the squad in no time.
Thus you can accomplish your main goal (of keeping your squadmates healthy) by not only treating them when wounded but also by contributing to destroying the enemy in the first place.