The thing with yoga is you have to watch some of the hyperextended stretches they go into. They can irritate some backs even further, where some don't get bothered from it.
It doesn't matter what exercise program you do, you need to have a plan and stick to it. This is why periodization works and should be applied when lifting weights to avoid cns burnout and potential for injury due to overloading.
Its not the exercises that are dangerous, its the people who are doing them wrong that give it a bad name. Everytime I hear "squats are bad for you knees," I want to punch that person in the face as they go up onto their toes when they bend down to the floor. Ever notice why catchers have bad knees? Well its bc they squat onto their damn toes and put excessive shearing force on their knees. The proper way is staying on your heels throughout the movement, chest up, knees follow direction of toes, and use a full range of motion. Anything less than that and you will get injured fast. Partial and half squats the the real cause of knee problems as is the "western squat" compared to the more natural "asian squat."
Bottom line: Your only as strong as your weakest link. Detraining(not training at all) will just cause more scar tissue to accumulate. Keep training and focus on bringing up your weak links in the chain.
