I'm really curious about those who don't carry a splitting device, and still build fires. I don't for sure know if I MUST split the wood first, I just always have.
I think I am one of those you mentioned that don't carry a splitting oriented device (axe, hachet or big FB) and still builds fires. With a folding saw and a 4" fixed blade I am good to go.
I think that splitting helps you out when making a fire with wet wood... but you can do very well without it. I mean that if you need dry core for kindling... a 3" diameter branch will have a dry enough core for that. There is no real need to split wood thicker than that to get something dry to burn.
In dry conditions you are better off making the fire with pencil sized sticks, then bigger ones and finally, anything over 3" burnt as it is... that way it will last longer. If you split them you will run out of fuel faster.
Mikel