Its dominance set the baseline that every later aggro leader was measured against
Did I mention it has vigilance and trample

Acid-Spewer Dragon Adult Gold Dragon Akoum Hellkite Akul the Unrepentant Alabaster Dragon Amareth, the Lustrous Ambitious Dragonborn Amethyst Dragon Ancestor Dragon Ancient Brass Dragon Ancient Bronze Dragon Ancient Copper Dragon Ancient Copper Dragon Ancient Gold Dragon Ancient Hellkite Ancient Silver Dragon Ao, the Dawn Sky Arashin Sovereign Arcades Sabboth Arcades, the Strategist Arcbound Whelp Archive Dragon Archwing Dragon Ardyn, the Usurper Armament Dragon Artificer's Dragon Ashmouth Dragon Astral Dragon Atarka, World Render Atsushi, the Blazing Sky Avaricious Dragon Avenging Hunter Backdraft Hellkite Bahamut, Warden of Light Balefire Dragon Beledros Witherbloom Belltoll Dragon Betor, Ancestor's Voice Betor, Kin to All Bhaal's Invoker Black Dragon Bladewing the Risen Bladewing, Deathless Tyrant Blast-Furnace Hellkite Bloomvine Regent Blue Dragon Bogardan Hellkite Boltwing Marauder Bone Devourer Bone Dragon Bonehoard Dracosaur Boneyard Scourge Boulderborn Dragon Brainstealer Dragon Brimstone Dragon Broodcaller Scourge Broodmate Dragon Broodmate Tyrant Caldera Pyremaw Canopy Dragon Canopy Gargantuan Capricious Hellraiser Catacomb Dragon Cavern-Hoard Dragon Chaos Dragon Chardalyn Dragon Chiss-Goria, Forge Tyrant Chromium Chromium, the Mutable Clarion Conqueror Clockwork Dragon Cloud Dragon

It absolutely ravaged the Standard of its day, but hasnt had much Constructed success since the downswing of Robots/Affinity in Modern
That kind of tutoring ability smooths out draws and keeps your strategy flowing, no matter how awkward your opening hand looks