Earth is somewhat "special" only in the whole shifting feet to cause people to imbalance. Other than that, any earth magic can do their job.
Are you defending or shooting on firebenders? If I must say what's good about firebenders, them go fist punchy and can make a simple flamethrower. Of course with the stupid stance. Mages on the other hand, depends on writers but go with DnD, needs prep time, gang signs and gibberish to cast.
And what you say is correct @RepresentingWrath , fire mage has higher output than firebenders fr fr. I thought FBs are boosted by extra fire source, not that they require external fire source.
Firebenders don't need an external fire source but the powers are tied to the sun. Nowadays authors abuse mana to do anything which is why you don't often see spells need anything other than mana. It's bullshit.
Other than that, any earth magic can do their job.