You are correct about the bracelets made to represent a decade of the rosary, but no one wears a whole rosary.
I remember how shocked I was when Madonna did it.
She has always been vile.
I do have a couple of stretchy rosary bracelets that have all the beads. (One I got from EWTN.). It is very convenient when we say Rosary before Mass, since my regular rosary will not fit in my purse. But you are correct, that it should never be worn as a necklace, and I, too, was shocked when Madonna did it. (I was Episcopalian at the time and even I knew it was a no-no.). But that was just the first of shocking things Madonna has done and she has slid further and further into the abyss.