I have yet to see a fire caused by an Arc. House fires I investigated years ago in Denver CO over a 2 year period.
Number 1, 11 cases cat knocked over the electric can opener trying to lick the goodies off the blade pushes the opener over and against the wall causing the motor to run until it fried. We found the can openers in that position.
Number 2, 7 cases Overloaded circuits causing wiring insulation in the walls to melt down and short out. No breaker trip.
Number 2a 5 cases Overloaded Xmas trees. Need I say more.
Number 3 3 cases Aluminum wire failing.
Bedroom fires number 1 cause cigarettes.
Never in my 55 years have I seen an Arc in a house start a fire. The only things I have ever seen arc in a house is a bad switch when you switch it or a plug being pulled or inserted while the device/appliance/light was drawing current.
So to this day Yes I believe they added AFCIs for fun and large profits.
I do install them but I don't have to like the added price to load center installs when the cheap electrician bid after me and did not install them.
I did digress a little from my own subject. But I got it out on my position on the AFCIs.