I don't think the problem is xp, as everybody earn assit xp anyway, but if you don't make kills there is no chance you receive looted items, may be medics (and tinkerer ofc) could received a small part of what has win the players they are healing.
[URL=http://"http://www.youtube.com/watch?v=P2W4FsDVKMY"]"Tu vois, le monde se divise en deux catégories, ceux qui ont un pistolet chargé et ceux qui creusent. Toi tu creuse. "[/URL]