I have tried to, an for the life of me - can't, imagine my needing a belt buckle strike a light....My main firelighter is a strike-a-light, safe in its pouch with its tinder, my spare is the same in the cook box, or a lighter, or a Swedish firesteel...
My belt holds up my trews...my back up for that is paracord...
If my belt was paracord and my strike-a-light
then I would constantly need to be clutching my waistband in one hand as I used the paracord and fire-lighting kit....
My belt already does double sevice as a strop (on very rare occassions) so I would also need to carry a strop with me.....
Nah - my kit works fine for me as it is...but I have to admit the firesteel buckle sounds like a fun gadget!