I have no doubt that our ancestors carried prepared tinder with them, however I'm sure that rather than exhaust their stock they would use whatever they could when it was available, and this includes tinders in the dead of winter..even at this time of year there is still plenty to find that will do the job. These tinders all took light from a spark from a ferro rod, a great many others will work from a match.
Fireweed, as the name suggests it works well provided you really fluff it up and allow a lot of air around it, the hogweed stems are a favourite of mine for helping the fire establish itself.
Buffed up grass, as you can see this works brilliantly.
That good old favourite of mine, Birch bark.
Buffed up Cleavers and dried bracken stems.
All these were found over the recent couple of trips and proves that even when it's raining or snowing you can still find good tinder at any time of year if you know what to look for.