It's more in line with your hair and scalp getting gradually more and more dry. Like, if the change in color is too drastic. What it does, is that it'll make you, uhm.. is "shed" the right word? Anyway, dry hair/scalp means shedding more than usual, as well as irritable/itchy scalp.
Well I'm not sure about hair color turning your hair white as a result however it does damage your hair. It's chemicals just like a perm does harm to hair or flat irons, curling irons, blow dryers, etc damages your hair hair color does the same.
Thing is we all as we grow older start to grey up or if you're a redhead turn white. I have been dying my hair and bleaching it for 13 years now (all different colors) and while it does dry it out a little its not this drastic situation people make it out to be. Plus there are many products to help color treated or damaged hair.