If it's a well-geared tank, such as a paladin or warrior, you can reduce those steps.
Step 1: Spam with AoW
Step 2: Rinse and repeat
Since I am incredibly confident I don't need a healer in that dungeon.

The excogs just wear off.
They do hit hard, it's just that the tanks you are healing are in good gear. If they went in with the worst possible gear, it does hurt a lot. The reason Holminster hurts so much is it syncs to the item level it's designed for (400).
They are generous in allowing undergeared people in, who didn't equip their quest gear, as well, to prevent people having issues doing the MSQ and that can increase the healing burden further.
This is how all
leveling dungeons are. The Endwalker ones hurt a lot too. Aetherfront isn't a leveling dungeon.
A lot of tanks best heals aren't available at that level either and obviously many of them get to a point where they can heal themselves without much sweat by level 90.
I think the reason it's like this is because SE wants gear progression to matter. If you improved your gear, you need to feel more powerful in content, with greater endurance and greater damage.