I've updated the Fire Elemental Team-building Guide with an overview of Fire's strengths.

Perhaps Fire’s greatest strength is that it can deal overwhelming spike damage with no debuffs at all, making it ideal against bosses with high debuff resistance, and also less vulnerable to debuff miss RNG. Fire is also excellent against bosses with thermonuclear-class Rage Overdrives (e.g., Accessory Quests), as it can store up damage and often bypass the Rage phase entirely.