Funny, my chiro has no issues with longing, as long as the circles are not smaller than 10 meters. If your horse is fighting you, you need to look at why, not blame longing. I have seen the Parelli circle games, and they are no different than longing. Since my horses are athletes and worked on a daily basis, they are longed before my butt hits the saddle. Just because some of these “name” trainers say it is bad does not make it bad … just because you don’t use or understand a practice is no reason to bash it or blame it as a source of trouble.
All longe lines that I have ever seen have a swivel snap that attaches to the halter, as does every lead rope … when used properly, a longe line with a stationary snap would not tighten up the halter anyway.