in a good team fight under current minecraft mechanics, if you target / damage the wrong person, its basically wasted because he will be automatically healed up by the ridiculous ammount of aoe heal spam being tossed around. You have to focus fire to kill people, and if you hit the wrong person, you basically wasted your spell.
Lets not forget heals have warm ups and can be cancelled immediately if you target the wrong person. Lets also not forget you are all terrible at aiming if you are constantly healing / targetting the wrong person!
AoE Heal Skills:
Healing Chorus: (15 + 0.45 per charisma point) health every 2 seconds over 10 seconds. ~28 hp every 2 seconds
Holy Aura (Paladin): Same as above, except heals for ~17 hp every 2 seconds.
Holy Aura (Cleric): (10 + 0.3125 per wisdom point) health every 2 seconds. Non-Self. 8 Heals. ~20 hp every 2 second
Holy Water: Party members including yourself within 7 blocks are healed for (60 + 1.875 per wisdom point) health ~116 HP every 14 seconds
Healing Bloom: Heal for (12 + 0.42 per wisdom point) health points every 2 seconds over 20 seconds ~25hp every 2 sec
BloodBond: While bound, you convert 30% of your magic damage into health (Drains 35 mana every 4 seconds, very mana heavy)
Fist of Jin: restores (3 + 0.2 per wisdom point) health to you, and (6 + 0.2 per wisdom point) per melee hit, at most twice a second. Returns ~7hp to you and ~10 to allies. At most, 20hp per second (Requires constant hitting of target though)
Chakra: Heals 107hp and removes 1 debuff
Healing totem: 27 hp every 2 seconds for 14 seconds at max level
Notice how the healers healing HEALING SKILLS? Notice how out of all the skills, a total of 9 are AoE Healing? And only 1 of them is an actual instant heal, 2 are passive skills (One of which drains a ton of mana).
Complaining about the AoE Heals (Most of which are HoT skills, so they can be out healed) is like complaining about DoTs or AoE attack spells.
Your constant insistence that everyone else sucks at aiming does not help your case as you just seem to be attacking anyone who doesn't love your idea of making HC healing more like MOBA healing.