They've got Lloyd's Beacon. That is pretty much tantamount to an endless supply of MP, as you can effortlessly teleport out of any situation. And when it comes down to it, there's not much difference between a 300 MP supply and a 500 MP supply. And that's not even counting the possibility of using Etheric's Staff. And Clerics have their own source of power. Power Cure outdoes Heal by so much it's unreal, combined with the endless supploy of MP garnered by Lloyd's Beacon, you have a fairly unstoppable team. Also, have you ever noticed how unholy effective Grandmastered Regeneration is?
Druids can do pretty much all that Clerics and Sorcerers can... its just that the latter can do them much better.
