This is so incredibly wrong. You can damage your knees doing any exercise, low impact or not, if you don't have the right equipment and technique.
We know that weight-bearing exercise, such as running, helps prevent osteoporosis and osteoarthritis. Repetitive weight bearing and motion are good for the joints, and running essentially does that.
"Running gets a bad rap, but running can strengthen the knee, and those who run throughout their lives have stronger knees than those who don't," according to physical therapist Michael Silverman, P.T., M.S.P.T., coordinator of the Tisch Performance Center at the Hospital for Special Surgery.
In fact, the largest study of runners ever completed, which was recently published in Medicine & Science in Sports & Exercise, concluded that running does not increase the risk of osteoarthritis (cartilage breakdown), even in marathoners. And, get this: Runners had half the incidence of knee osteoarthritis compared to walkers.
Obviously if you have poor form or crappy shoes, then yes you'll get hurt. OP is looking for advice on how to prevent that. Just because you're terrible at something doesn't mean you should talk negatively about it.