This! My wife had chronic knee pain that no one could figure out given her relatively youthful age. A smart trainer spotted that her leg muscles were very, very weak. She strengthened them and now has no knee pain - and in fact is running about 20-25m per week where before she assumed she'd never run again.
Well, I happen to have personal experience here. I had pain on the outside of my right knee for a few years. I also had clicking in my knees whenever I would squat down, ever since I was a teen. One day, I did an hour of Bulgarian split squats[1], which is a one leg exercise -- I did it with no weight. The next day my knee pain was essentially gone. One day!
It turns out, after reading up on it, unilateral leg strength is important for knee health. The right muscles being strong and coordinated takes stress off the tendons, ligaments, and cartilage that support the knee. Doing one leg squats teaches and trains your glutes to balance and stabilize your body on one leg.
But will strength training not wear out the joints?