Not exactly, he could have made a 9x9 room around the spawner (I'm assuming it is a spawner) with the middle 3x3 going down a 40 block shaft. Inside the rest of the room are conveyor belts going towards the shaft and the ground level could now be 9 hoppers instead of 81.
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Not as much vertical space as a vanilla solution, but still quite relevant. You wouldn't want to stop the mobs inside the spawn radius of the spawner as this can greatly reduce spawn rate if it's a just a regular spawner (endermen spawners can be found in packs with the roguelike dungeons mod such as Horizons and Monster). If it's a powered spawner like from MFR or the like that just spawns things regardless of conditions, then it'd make more sense to squish them all through one hole instead.