Be honest - when 10 rats are so close together that they look and act like 2 rats, and when you kill all 10 with one swing anyway, what’s the difference between 2 rats and 10 rats?
Hordes are fun gameplay element but they are a 1-trick pony. They also actively interfere with any other gameplay elements, and force the entire game to merely be “horde” type gameplay. This is because hordes are spatially restrictive to the player. They body block you and prevent you from making other counter moves or strategies. A SV is not especially hard, but surround him with slave rats so you physically can’t dodge the SV and now he’s a major threat. Except… that just means it’s the slaves that are the real threat, so all the gameplay ends up being focused around the horde and there’s no room for creatively made enemies or a variety of gameplay.
Case in point? Beastmen. Fast, brutal, with new moves, new weapons, new strategies. They were absolutely overpowering to the point that V2 was ruined by them, and Beastmen have been constantly nerfed. The sole reason is that there are too many of them! A enemy that dodges is nothing special, an enemy with a long spear is not a game breaker, but 50 of them are. Because the game spaces is physically filled with foes, changing tactics and counterplaying the new enemies was not possible. They would have been perfect as patrols, or hunting parties, or ambients, but as a horde they literally broke the game.
Hordes also downplay teamwork, since it only takes a few body lengths of distance to be physically cut off from your allies, making the game “solo with friends” and not a true team game.
The optimal horde-game design would have smaller hordes, allowing for more flexibility in both design and gameplay. Or it could have less frequent hordes, with other encounter types in between them.
Therefore, please, make DT have smaller (or less frequent) hordes then V2 so the other mechanics of the game have a place to shine.
Also there are performance benefits, let’s not forget that.