For as long as we can remember, static stretching has been considered a cure-all for injuries and maladies. What's the first thing your coach tells you to do when you get hurt? Most likely "go stretch it out." While static stretch serves a purpose, it's really not a cure-all.
First, it's not really a good warm up. Most folks are up to date on this and use a dynamic warm up, but I still see some teams do static stretching prior to activity. (Just as an aside, static stretching is where we hold a limb at the end range of motion of a particular joint for a set time; dynamic stretches include continuous movement). Using static stretching as a warm up has actually been proven to decrease physical outputs.
Second, most injuries don't require basic static stretching. Take a muscle strain, for instance - the muscle is damaged because at some point it took on too much force at too great a range of motion. Stretching the muscle even further doesn't really accomplish anything positive. There are some cases where physical therapists and doctors might use stretching during a rehab protocol to help regain a lost range of motion, but this is for much more traumatic injuries that have greater impact to function and require a more comprehensive healing method. But, speaking of range of motion...
Third, static stretching isn't always the solution to a "tight" muscle. In many cases, tightness is a symptom of something else, like neuromuscular patterning or stability in an adjacent segment/joint. In this case, stretching accomplishes very little. Have you ever met anyone who says they stretch all the time and still seems very tight? It happens fairly often - stretching isn't the answer to every problem. In some cases, it even makes the problem worse. A kid with limitation in the hip flexor might go to stretch the hip flexor and instead just arch his lower back giving the illusion of hip stretch, but really create low back problems without actually doing anything to the hip. In reality, the problem might just have been a weakness somewhere in the hip complex that made it not willing to move into a full range of motion.
The point of this article is just to point out that stretching isn't a cure-all - it's one of many tools that we have, and to be honest, it's one of the smaller, less useful ones. Stability work, soft tissue work, modified stretching with small movements and controlled isometric contractions, and strength all tend to get better results for increasing mobility than stretching.