@ABoyNamedBoobs03 if you have been driving as long as I have (30+ years) you realize that anything larger than your thumbnail is going to block your view of oncoming traffic, even from a distance. For comparison, holding a nickel between your thumb and forefinger at arm’s length is the approximate size of the moon in the night sky. A car is MUCH smaller than the moon, and even 300 feet away, that same car can easily be blocked by beads (or anything else) hanging from your mirror.
Drivers have enough distractions, and our vision isn’t as great as we would like to think, and besides that, just because you can hang things from your rear view mirror, that doesn’t mean that you should. Why would anyone hang rosary beads on the mirror? Is she advertising her religion or is it in case the Pope rides in her car, so he can see she is a good Catholic?
It’s like those CD holders that go on sun visors. If I had a dollar for everytime I’ve been blinded by sunlight reflecting off someone’s visor CD collection, I could quit my job and spend my days on the corner, waving at the other people driving by. =)