Barbarian magic suppression skills...

In a battle against a mage, you can't hesitate; you need to eliminate all their troops as quickly as possible. Allowing them to cast more than 3-4 spells can lead to a disastrous outcome.

You say 3-4 casts? For example, if an Orc in a somewhat prolonged match doesn't have Slow and a Necromancer consistently casts Mass Slow, Mass Dispel, and Haste (attack perk), while the Orc can only approach, the game is over for the Orc. As is the case with casting Sign of the Mage, Enchanted Arrow (Ballista, Rain), etc. Slow is useful in the endgame, but it actually hinders development during the early game; otherwise, it would be a fairytale. The Orc is strong, but extremely vulnerable against Dungeon, and other magic schools also give him a hard time. And the main thing is that no single race is tied to only one magic school; mages, in general, are experts at surprising with their choices. So, you have to guess.