It's just an automatic reflex like using a valve lifter on a kick start single.
I did a cruel thing once....
I had a Velocette 500cc single and along with other members of the "old British bike fraternity" I was asked to put it on display during the town show. A smug young lad came up to me and said that he couldn't see why we old buggers made such a big fuss about old English singles, he after all had a 600cc Kawasaki trail bike that had no electric start and he found it a pussycat to start.
Needless to say I invited him to try his mettle and kick over the Velo.
Being half smart he asked for some basic info on procedure - I told him to turn the fuel on, juggle the "tickler" until fuel came out, then push that lever on the left hand side of the bars all the way forward, open the throttle about 1/2 way and then "go his hardest".
Evil bastard that I am, I completely forgot to mention decompressors, and left him with a flooded carb, fully advanced ignition and half throttle.
Well, he leapt up and came down with a mighty kick, the Velo however kicked back just as hard and the lad sailed through the air and landed about 3 feet in front of the bike.
Before he hobbled off in the arms of his friends I retarded the ignition (and turned it off), turned off the fuel and of course, closed the throttle. After prodding it through twice, I turned on the ignition and gave it a gentle prod and it sat their quietly idling away.
"Technique son, it's all about technique" I said as the lad went away with a new found respect for both old English bikes and their owners.