The problem isn't the difficulty of healing, healing in dungeons is easy enough, the problem is people's expectation from a healer... You're not just supposed to heal you have to DPS as well which is perfectly fine except when the tank is undergeared/doesn't use CDs/Stays in offensive stance/Eats every AoE and pulls the whole dungeon... That's where things get messy and when the tank dies because of any combination of the above reasons it's the healer who is a scrub and responsible for it all.

Though even when that happens if you are SCH it's still generally easy to do huge pulls with Fey Union/Excog/Adlo.

But yes unless your party is incompetent healing is pretty easy until you get to Raids/Ex Primals which is where the real fun/stress begins.