Toph said..
I think it would be an ok practice in areas that it is a known common practice. I do think it would be better if the bouys or fenders were floating on top so you could see a string of bouys.
I think it would be prudent for all sailers to follow or expect a standard practice and be predictable. The sailor that lays out 50m of chain in 5 meters of water on a calm day is also a hazard.
What a load of rubbish , Many a yacht has been lost because they didn’t put enough chain out on a calm day and was hit by a powerful squall .
in shallow water you need more chain for it to work .