with a forest full of downed Birch it seems like you would not need to carry it in but being able to pull out a hunk of bark from the food pack and put a match to it beats bashing around a wet brushy forest to find some and i think it makes a better fire starter than something you could buy.
I've been caught twice where it was extremely difficult to find or process dry tinder so I'm a big believer in bringing some with you. Free from Mother Nature is my favourite kind!