In ritual magic, additional participants can take consequences and invoke aspects.
Sacrifices can only take consequences, usually unwillingly, even unto death.
Both are usually done in preparation and the casters have to be involved for the duration.
This means that with 13 wizards who each invokes an aspect and takes 2 mild consequences, you have a ritual complexity of 78 + Lore + other bonuses. Sacrificing three lives instead gives you a ritual complexity of 60 + Lore + other bonuses even for a single caster. Now, think about combining the two. Or, like, feeding a couple thousand people or devouring hundreds of powerful spirits for the ritual.
Yes. Ritual magic is scary. That's why dark wizards, who don't have a problem doing blood sorcery and ritual sacrifice, must be stopped at all costs. A single dark wizard who dominates enough people in a small town in the middle of nowhere then kills them all in a big ritual could cast a spell that erases New York from the map, makes him into a demigod, kills thousands of people that share blood anywhere in the world, or summons a major Abomination from beyond the Outer Gates.