I'm a middle school coach and as several stated above, the UIL makes us teach the Atavus method. A big gripe I have is coaches are required to get recertification every 2 years and we have to pay a $40 fee to Atavus. It's a fucking racket.
I have been around long enough to have experienced the change from a coaching perspective. With Atavus, we coach you strike your near shoulder to ball carrier's near hip. Head goes behind, you are supposed to wrap and drive. It is simply easier to break tackles because we are over emphasized on a limited amount of the body making contact.
Just a guess, but I think another factor that makes for a lower success rate (Atavus method) in football compared to rugby is the shoulder pads. If you are going to put such an emphasis on the near shoulder/arm wrap, the pads do reduce your arm range of motion and make wrapping more difficult, especially at my level where the pads are just as big as some of the kids.