Those who do not play Cleric don’t even need Heal in the first place, no idea why they are mad.
Swordsman has Peltasta to reduce all damage to nearly nothing, or at least Bear for over 20% damage reduction. Getting a good shield and plate set negates most of the damage.
Archers can attack from afar and have lots of CCs to keep enemies away/disabled. Quarrel Shooter can help with survival if needed.
Wizards have permanent 20-35%+ damage reduction, a lot of CC (Psycho/Cryo) or damage mitigation (Shadow/Sage/Featherfoot). If they equip plate & shield, they can become as durable as a non-Pelta Swordsman. Also able to use Restoration Scrolls on harder content due to natural SPR growth.
Scouts have high evasion and thus evade about 50% of all attacks. Enchanter allows for additional block (halving damage), Linker for CC, Assassin & Bullet Marker with iframes and Cloaking to negate getting continuously targeted.
At the moment people are simply undergeared for content if they die all the time, or did not invest into the right attributes.
TOS in Re:build offers a lot of survival options throughout all Class trees and you can pick any of them to make your life easier.
If you don’t pick any of them and still play as if you’re permanently protected you’re doing something wrong.
Move, learn to pot, upgrade your equipment, prioritize survival skills/attributes before damage ones if you fail to survive. Learn about the monsters, their attacks/attack patterns, time & match their attack delays with your attacks and movements. Use sprint/dash if possible/required.
As Cleric I only have Heal and I only use it for myself. I always need to be close to the enemy to deal damage so I cannot spare a single Heal for someone else. I don’t see anything wrong with it either.
Those who play the game always have the choice to play Cleric and have Heal or play something else and thus have to make do without it.
It was their choice to skip Heal and was their choice to skip the survival skills/Classes in their Class tree, so the Cleric cannot and must not be blamed for the bad choices made by others.