You know they will bring some food and help you out in the kitchen
(Extended Art, Surge Foil) Better than everybody dying
Therefore, it is very easy for every customer to pay.
In a deeply interactive format playing only sorcery speed is annoying, and it also stops a ton of cards such as Cascade spells, Shelldock Island, Instant Madness cards and Bring to Light
You can play out vampires one by one and get an extra +1/+1 on board for each one you cast, or you could play token-makers like Charismatic Conqueror and Bloodline Keeper // Lord of Lineage to spread that vampire lord effect across more bodies with a single card from your hand
Much like the 10 2-color Ravnican guilds, the five 3-color shards from the Shards of Alara MTG set have become a sort of shorthand for the combinations of colors that they contain