I feel that is a courtesy type thing, and it works both ways. If I'm out on the water or ice with some buddies joking and cutting up, and you decide to bring your little crumb-snatchers and wimmim folk out and set up next to us... it's too bad for you if you can hear what we say and don't like it! You can move on down the line because we were there first!
On the other hand, if you are there first with your family and we should decide for some reason to set up within ear-shout of you... we will keep it civil out of respect for your family. Normally though, I would not set up next to a family... because I do like to joke and cut up with "colorful" language.
On the open water I keep my voice down (especially at night) because I know how sound carries, and I remind others to do the same.