IIRC BitLocker with pre-boot authentication mitigates DMA attacks. Most Windows hardware doesn't come with FireWire or Thunderbolt ports nowadays. Microsoft recommends pre-boot auth for devices with DMA ports.
These are fair points. But for businesses in particular, it's a problem since many skip on (or are unaware of the need for) pre-boot auth, and business laptops still pack FW ports, if not on the laptop itself, then surely on the docking station.