Why leave a diesel running while filling it up?

[Chas_svo]

I thought it was just to annoy everyone without 200 yards of those stinky, rattling biatches...

[payne5757]

^yup. Dont worry, youre not gonna accidentally ignite the diesel because it running or with a static spark from your shirt rubbing on the car like you see in worlds craziest videos crap. Diesel doesnt ignite easily at all.

[Mysticcobrakilla]

Keeps the a/c kicking!

[MattB]

I've never got a good answer. I understand if it's below 40 degrees, or the truck isn't warmed-up yet, but what if you have been driving 3-400 miles, and the temperature is normal outside? Is there a benefit to leaving your truck running?