And I'm saying that squatting to full depth doesn't increase the load on your knee joint, it increases the eccentric load on your hamstrings and glutes. Also strengthening the muscles around a joint is good for the joint. Barbell squats have absolutely been good for my knees.
IMHO squats carry more injury risk for the back than the knees, which is why it's important to use strict form and use a weight that doesn't cause your form to break down.
Definitely true. I've seen several people hurt their back while squatting (I've done this myself, albeit a very minor injury). I can't recall ever seeing someone hurt their knees from squats. I'm sure it happens, but it isn't as common as many people seem to think.