Doctors correct me if I'm wrong here...
With /assist <name> as it is now doctors actually have it a bit easier (assuming target doesn't drop right away which sadly it does like 75% of time when called) as they have to heal only one target out of whole zerg and every /assist points at it.
With /assist <name> nerfed/changed/removed/whatever they would actually have it harder as they would have to oversee whole zerg and not just person currently called. So IMO /assist could stay as it is.
/assist <name> shouldn't exist in such for as it is now as it destroys mass PvP (there is no fun in waiting 30 min for battle to start just to be called and die right away) and it dumbs PvM even further.