Destruction has 60 damage thunderbolt which gets +50% damage and then dual cast. Which gives it 198 damage. Notice that 198 is higher than anything weapons can do? This is the reason destruction doesn't "scale" as you level the scale... because it's doesn't need it. The only thing that pushes melee/archery out of whack is alchemy. Even using enchanting and smithing you do LESS damage as a warrior than you do as a Mage using the same.
Correct, until you notice this:
Level 100 Enchanting (5 X Enchanter, Insighful, Corpus, Extra Effect: 8 Perks) (26 Perks Total)
Daedric One Handed Sword: 126 Damage
It's still one handed, which means 126 damage in each hand. If you go for dual wield, which is the equivalent of dual cast, the number becomes this:
Daedric Dual Swords : 252 Damage
Not to mention that with a bit of patience, you get these numbers:
Level 100 Alchemy (5 X Alchemy, Physician, Benefactor: 7 Perks) (33 Perks Total)
Daedric One Handed Sword: 180 Damage
Daedric Dual Swords : 360 Damage
Gear fully Enchanted 4 X Weapon Enchants and 4 X Armor Enchants.
Daedric One Handed Sword: 518 Damage
Daedric Dual Swords : 1036 Damage
And this is only about the pure damage. If you include the Dual Flurry (which increases attack speed up to 35%), the effective number goes even higher
This synergies well with the fact that as the level of enemy increases, so does their health, which means one can keep playing without changing their playstyle. But as you can see, the 198 damage thunderbolt stops there, which means as the enemy gets stronger, the battle takes longer