I don't think I would listen to anything that person says. Some people like to get separate bobbin winders for various reasons (such as for a longarm, or because the bobbin winder on their sewing machine is broken), but I've never heard of a bobbin winder doing "something" to a machine. Maybe sometime, somewhere, (in a galaxy far far away?) there was a sewing machine that didn't get along with its bobbin winder, and that's the cause of this advice?