Stretching microscopically tears down muscle tissue?

This is not entirely accurate. Stretching muscles does not microscopically tear down muscle tissue.

During stretching, the muscle fibers are elongated, primarily involving the sarcomeres -the basic unit of muscle contraction- and the connective tissues surrounding them. It is true that at extreme ranges or improper techniques can cause strains or microtears in the connective tissues, but with proper technique and gradual progression, stretching benefits the body without tissue damage.

In reality, stretching induces the remodeling and adaptation of muscle fibers, fascia (connective tissues), and the nervous system to become stronger and more flexible.