Stretching science shows that it doesn’t do most of what people hope it does. Detailed article.
www.painscience.com
Would suggest everyone to read the article I linked. It is extensively backed up with references to scientific studies.
To VM's point, this-
Exercise is the closest thing there is to a general miracle drug and
strength training is one of the best types of exercise, practically like magic: healthier and more efficient than most people realize. It’s
also widely accepted as a major part of injury rehab, and stretching goes along for that ride. Although it’s not taken anywhere near as seriously as strengthening is, millions of athletes, trainers, coaches, and healthcare professionals still consider it to be a staple of rehab.
To Gbg's point-
There is really only one stretching benefit that seems to be clear and (almost) uncontroversial: it does actually increase flexibility. Even just plain old static stretching. For whatever it’s worth, people
do seem to be more flexible when they stretch regularly for a while. Real elongation of tissue is elusive, and hard to sustain; but it can be done. The phenomenon is widely observed, and seems to have been confirmed by experiments. I previously cited Marshall et al — a decent, recent example — and there are more (cited and discussed below). Less than you’d think at this point in history, though! There’s hundreds of studies of anything these days, but not this.
So, you can get more flexible “for whatever it’s worth,” but what
is it worth? Is it actually a benefit? I will start by arguing that is not worth much to most people, even athletes.
The value of flexibility
“I want to be more flexible,” people say. Even when they have normal range of motion in every joint. What’s this about? Why are people so determined to be more bendy? What is it you want to do with that super power?
What exactly are you planning to do with your flexibility?
The fact that there are actually several elastic superheroes speaks to our genuine desire for greater range of motion. But the reality is that hardly anyone actually
needs to be more flexible. Most people have a normal range of motion — that’s why it’s normal! Unless you are specifically frustrated because you lack sufficient range of motion in a joint to perform a specific task, you probably don’t need to be more flexible.