No Smoking

I think it's odd that on airplanes they always announce that
"There is NO smoking allowed on THIS flight".

Isn't that common sense?
Are there any flights where smoking is allowed?

My guess was that there was once a flight where someone showed up and started chain smoking.
A flight attendant told that person to stop because everyone was having a hard time breathing and the clouds of smoke were really annoying.
The person then refused to put out the cigarettes because he doesn't like to be told what to do.
But then after shouting at everyone for awhile he lost his voice.
But then just before he lost his voice he was able to barely utter the words:
"Fine I'll stop"
Then he did stop, but then he ate the rest of his cigarettes just to spite the people who told him to stop.
This caused him to vomit on everyone.

After that happened they probably decided it would be best to just make the
"no smoking on THIS flight announcement".