There is a big difference between mobility and stability. Mobility is how far something can move, stability is the means to maintain equilibrium while facing external perturbations (so that you don’t fall over). Only focusing on mobility training might not be the best idea. You want to be able to control the ranges of motion you develop. This is where forms of stability training can be beneficial. When talking about stability training, we don’t necessarily mean standing on balance balls and unstable surfaces, we mean building strength through ranges of motion. For example a form of stability training could be building the strength to handle more weight at the bottom position of a lunge. The distinction between mobility and stable is critical to understand. Yes, at times we need to find a way to increase the range of motion of a limb but to simply increase range of motion without developing strength to go along with that new found range of motion could potentially do more harm than good.