As someone who coaches a local amateur sports club: at our level, the main reason to learn proper biomechanics is to reduce risk of injury. (At a higher level, it's also useful for getting those small advantages in effective reaction speed and positioning.)

Changes in direction are a really, really, really common cause of knee, ankle, and foot injuries. There's a _lot_ of force on fragile joints when you turn, dodge, fake out, etc. at speed - and especially for occasional / amateur athletes, who often don't have a high base level of strength and mobility.

It looks silly, but I'd rather our players look silly than tear ACLs or rupture Achilles tendons. (Plus in Canada, those tears and ruptures also cost taxpayer money - a whole lot more of it than making a quick video!)

Probably good for rehab after injuries.