Ah when Mr Rh and I saw that a couple of years ago we didn't see the 'tributes to loved ones' and thought maybe it was spontaneous art-making and somehow it gathering momentum until everyone who stops there feels like they want to make one too. I mean it is quite a spectacular spot. And there's lots of material hanging about.
I'm trying to think of something similar. I can't though. I can only think of some craze like padlocks on venice's bridges.