I suggest you do the same then look at just how many motherboards actually had an Apple Firewire, or Sony iLink port, or if they did/do how many of them have more than one. Firewire is a niche market as it always has been that never cracked the mainstream market in the way USB did and continues to do.
Quite a lot. Most OEM's included it on their 2000-2005 desktops. Notably Dell, Sony, IBM/Lenovo, and Gateway. It was more prevalent on their portable computers than their desktops. Intell had a few boards with it as did ASUS. Even cable TV boxes have the option of FireWire.