I mean, it's just a BFA thing where you actually need a mage for the Arcane Intellect buff. Class exclusive buffs weren't a thing for many years untill BFA happened.
Actually think its such backward design aswell, it just locks a large part of your roster in place due to the buffs. Especially when it comes to the Monk and DH buffs since there is no scrolls to compensate for them.
Not claiming it's much better to be an Elemental shaman compared to being a mage though don't get me wrong, I'm very aware of how useless Elemental has been for the majority of the raid tiers the past expansions.