When it rains hard 3/4" stone also floats. I could see that being an argument if when it was drizzling it was running down the driveway. I can see how rubber mulch scares some landscape pro's. We sell a bunch to local schools and daycares and they rave about it. As long as it is prepped right and is contained there should be no problem. Also the biggest problem of it disappearing is people takeing samples home in their pockets.