Not true. Many consumers use firewire external hard drives.
I don't know of any. Most consumer level people I know (I define consumer as office worker types, college kids, housewife, etc) don't even know what Firewire is or even have external drives. The ones that do buy the cheapest drives possible, Western Digital USB external drives, or whatever is cheapest from Office Max, Staples, or Best Buy.
I wouldn't call people who know what they're doing or doing this stuff for money, consumers.