You misunderstand. There are some debuffs that healers can't remove. Like Esuna doesn't remove them. Some of these like doom require a mechanic to be managed to clear it by the player who has it or they die. The healer can't save them. Others like environmental debuffs affect the type of amount of damage the player takes and stays on them and can not be cleared by the healer. While the debuff may not be cleared, the player should learn to be mindful of their own status afflictions instead of ignoring them completely, which is what a lot of the players are doing now.