Jockey wheel - up or down

I just don't understand why some people wind up their jockey wheel when on site.  You will get those who argue that you should always leave the jockey wheel down for added stability, and those who argue that it should be down because the corner steadies are not 'fully load bearing' or whatever.

My arguement is that when you arrive on site and you unhitch, the jockey wheel is down.  When you come to hitch up the van, the jockey wheel is down, so why put it up once you have the caravan sited only to put it down again to hitch up at the end of the stay.

What exactly is the arguement for raising the jockey wheel?

David