dungeon helpers

[Saseal]

Not true in the case of WoW. Squishiness is completely dependent on the healing class you play and there are tons of healers (there's six different healing specs.)

And in RO/Ragnarok Online, Full Support/FS Int/Vit priests with an uninterruptable cast gear were near unkillable xD; (used to have to get an Asura monk to kill with Guillotine Fist, along with a mob of peeps to bring down shielding spells like Kyrie..... which is basically stone skin)
People used to use them to tank in PVP/WoE and some MVPs/bosses/dungeon mobs instead of the actual tank classes...
ME priests, though.... not so much