I think I would like to see encounters scaled in such a way that damage mitigation, avoiding attacks, an aura-style regeneration, and/or triggering heal procs from damaging an enemy could sustain a party.

Where the inability to avoid an attack or a heavy hitter targeting someone other than the tank would put a hole in this unity, requiring more direct healing to recover.

i.e. Paladin's regen assisting the melee front, haven't used Lancer since 1.19 - don't recall if the Speed Surge effect was present (party members receive HP for attacking the enemy).