The cruise lines also won't stop anyone from saving chairs etc etc etc.
Unfortunately most of the rules of behavior they print over and over in their daily programs aren't worth the ink used to print them-- in terms of enforcement.
But I'm not sure the standard we as passengers want to set is for everyone to do what they want, and what they can get away with. Maybe I am delusional, but I think the vast majority of cruisers would like the bar set higher than that.
But then, one cruise recently I did see someone bringing a hibatchi onboard, so you never know! Maybe soon we'll all be tailgaiting at the pool.