The reason you see lots of high school kids getting knee injuries playing football is because they are getting away from weight training in lieu of agility, core, and other b.s. training methods. Most of the H.S. training programs are being taken over and administered by local hospitals. I guess they see it as a way to generate business. Knee surgeries are a big ticket item.
Weight training not only strengthens muscles, it also strengthens tendons, ligaments and intestinal fortitude.