We don't. We give you the flexibility to use the case however you like. Some boards have a total of 6, and then if you use a pci sata card/RAID card, etc, you can get more.
On the flip side, you can remove it and use it as a high end gaming system.
The "Diablo" build:
Intel Core i7-3770K @ 4.7GHz (Prime95 -> 81C)
Corsair H60 + CoolerMaster XtraFlo Red LED PWM fan (2200rpm)
Asus GTX670 DirectCU II OC
Asus P8Z77-I DELUXE
G.Skill RipjawsX 2x8GB 1600MHz (1800MHz O.C. with same timings and voltage)
Corsair Force GT 240GB SSD
Corsair TX650 V2 PSU
BitFenix Prodigy Black case
BitFenix Spectre Pro Red LED 230mm case fan (undervolted via included adapter)