Voadam
Legend
Similar perhaps, but it wouldn't get an unconscious ally back on his feet, so there is a critical difference.
Other than that I agree with you that a leader should not be defined solely by the fact whether he can heal or not, even though it is an important function. Reducing damage, other ways of healing and giving temp hitpoints should work just as well...
True, healing and buffing are not the same.
Healing does not make you do your job better, it means you can get back to doing your job after being impaired and do your job longer in combat. Healing never increases you over your baseline.
Buffing can make you do your job better. Hit harder, be more accurate, attack more often, move quicker, etc. With buffing you go above your baseline.
I think you could conceptually lump these two into the same role as 4e did or separate them out into their own roles. 3e's Mini handbook had a healer class and the marshall, for example which both seem conceptually to be viable classes for a group in combat.