They are quite bulky - one of the bulkiest ways of starting a fire I know. Much bigger than a Bic or a Sparklite or matches or whatever. Mine has a danger of drying out and you have to keep the seal lubricated (I use vasaline), so it is not really an ever-lasting device even if you can improvise tinder.

If I'm somehow incapacitated and a stranger is rooting through my equipment looking for things that will help me, and they see the smooth wooden tube with the pot of vasaline next to it, "firelighter" may not be the first use they think of.