I believe that your take on this thread is an East vs. West kind of thing. Most (not all) campgrounds specifically prohibit dumping of gray water so common sense and respect would say not to do it.
There are some places that don't speak to it and I have been in a few where the people in charge are glad to get some water to surrounding plants and bushes. "Dumping" as in simply emptying your tank right at the site is never a good idea. Running a hose out to the edge and into some bushes will do little harm and a lot more good in the end.
If your gray water "smells" then you have a problem with your tank. We treat our black tanks but few treat the gray tank. If you are worried about the smell then take care of the tank. I use biodegradable safe chemicals in the gray tank.
I walk through campgrounds all the time and see tent trailers with a bucket outside catching all the dish water. I also watch these campers take the bucket to the nearest bush and empty it. Tenters do the same and have been doing it for decades.