"Stephen, that is not a requirement in the national forests that I've traveled in for the last several years now. I go to the permit station, they issue me the wilderness permit, and there is nothing said about campfires. They sometimes ask me what kind of stove I am carrying. I tell them Esbit, the permit is signed, and I'm off.
No, there was no requirement for me to have a campfire permit in the Angeles National Forest, either. I camped in an established campground, the one that the feds suggested to me."
Established campgrounds generally do not require the campfire permit - though at one point when we were in Sequoia NF last year, when fire danger was high, there was a 6 hour period when the campground host said we would need one - and I promptly whipped mine out! But that would explain the Angeles NF reaction.
However, in the three NF here in SoCal that I regularly hike in, plus three farther north (Stanislaus and Inyo), I've had to show my campfire permit to get a wilderness permit. No exceptions. So...how much are ya paying the office personnel where you hike to pass you on the campfire thing? ;)
Seriously, back to Nick's point, if folks followed the CA campfire permit requirement of clearing combustible out to 5' from the stove, I doubt even an alcohol stove knocked over could start much of a fire.