Heat distribution? Maybe the carbon is wicking away the heat faster than it can on the edge, or the edge provides sufficient surface area for the flame to take hold.
FWIW, Doritos burn plenty good as kindling, or if you have a knife you can make feather sticks.
Long time camper/backpacker here. If the question is is it scientically harder (12%!?) then maybe. If the question is it practically harder, then no. My anecdotal experience is that it might be easier in winter due to the drier climate.
I knew an older guy who would put a small piece of pine in his pocket while we were working outside in Maine in the winter, and when it came time to make a fire outside, he’d take it out, put it in the bottom of the kindling pile and his fires would always take off.
When I was in the Navy learning about fire fighting, they taught us that you need four things to make a fire. Oxygen, fuel, (the exchange free radicals but this idea comes and goes) and heat. Not fire as many instinctively think, but heat. Then I understood why it was actually harder to make a fire in the cold.
I think it’s harder in serious winter, but for other reasons than the need to heat the fuel a little more. For instance, cold (and heavy clothing) makes your hands and everything else clumsier, snow everywhere gets things wet, you might need to do a lot of work just to have somewhere to build the fire if there’s deep snow cover, and butane lighters don’t work well or at all below 20F or so.
The largest factor is the frozen but ‘seems’ dry ground. Frozen water is locked up in that and it is a pretty large cold sink which must be melted, then evaporated off, all while taking heat away. If you can get your fire on a insulated surface you will find it goes much better.
When I was hanging out with Tibetan nomads one October (snow starts in September and October was never above freezing temperature cold), what they did was the following:
saved partially burned kindling and kept it inside their clothes
light with a single match. And these were crappy matches with almost no head and a really thin stick. I seriously had trouble lighting one of these and keeping them alight. The local Tibetans could almost always strike once, and then get an okay flame
The real trick was a small portable bellows that at least one person in each small group had. The bellows was made out of a sewed sheep skin and a small metal nozzle. It took a little practice to make the bellows work (you kinda folded it with your left hand, and pumped with your right) and once you got the rhythm going, it was pretty easy.
The wood was damp and you pretty much had to keep the bellows going constantly.
The other fuel was dried yak dung. It burned pretty hot but quickly and either I was used to it or it truly didn’t smell much different than dried grass.