@AnotherGuy well, there is a catch, most medics are close to their team mates (only if they’re not idiotic and run on their own with probably must be newbies) and if a Phantom decides to jump in the action to disable the Revive Gun,Defib or whatever it is: 1. he would be seen. 2. he would be dead since almost all the team mates are close. And also, Sparks and Phoenix are much faster than phantom, so they both can basicly outrun him or kill him by bouncing around every wall.
@Naonna right, reviving IS the core of a medic, but also healing. another thing to make the EMP field more “fair” would be to atleast make the charging time of the revive gun slower , the defib charging time also slower and the healing pulse to like, heal 10 points of health less.