I worded it that way because we're all so fond of nitpickery. I actually hate the entire "overwrites" thing on AST and SCH, but without it, you get two shields, and that ends up bringing the "lazy healer, with nothing to do" issue back into focus. I'd like to see SE find a way to make the regen and shield effects "stack" but only cut their potency in half when stacked rather than over-write them, but I suspect the real reason they made the shields overwrite was to reduce the buff clutter on screen.
Still, the point I was trying to make was that by removing Protect and Esuna from the WHM kit, they can't make content designed around those skills existing because players may not have them. They need to give protect back to WHM-only, and have AST and SCH have their own flavor that can stack with it. So that logically requires giving WHM back stoneskin in some way so that content can be designed for party shields, otherwise the AST and SCH have "Bonus shields" that just contribute more to the "lazy healer" problem.
Like it would make more sense in the long run to just give up on making the healers "unique" in any aspect that would tilt the healing balance. Like you can see the thought that went into AST originally, and how it backfired (like really, a slight nerf to the healing potency, but has to be made up with RNG-based buffs?) The healer needs 6 skills, everything the healer does should be connected to either keeping the shield up, keeping HoT up, or casting party/spot heals, while doing no overhealing:
Spot Heal
Party Heal
Spot Shield
Party Shield
Spot HoT
Party HoT
With any shields at all, with WHM means the Lilies and confession stacks for Plenary Indulgence aren't available, as those are only given for healing, not overhealing. AST brings RNG buffs, so you may as well assume they won't use them, and the SCH brings a fairy that has buffs that they may forget to use, or use at the wrong time, or may not even use the fairy that benefits the most. The WHM brings no buffs presently that you can't get with AST, and even SCH has access to protect.