I am perhaps the only Chinese martial artist publicly advocating against rooting. If readers are aware of others please let me know. I know I'm not the only practitioner who avoids rooting, but it has become such a standard instruction that most other rooting skeptics just avoid discussing it.
Because language can be confusing, let me try to define it. Rooting is using friction on the bottom of the foot to resist incoming forces from an opponent, or using that same friction to push an opponent away. (Feel free to add your own definitions in the comments.) Obviously to make this work, one needs to develop dynamic structure throughout the body.
How did I become a rooting skeptic? Twenty years ago I was giving private Northern Shaolin lessons to a high school football player. The student had been training with me for a couple of months and I decided to work on rooting skills with him. The method I chose came from the Xingyi taught by Kumar Frantzis. It involved a progression of challenges where the two of us hold opposite ends of a staff and root against each other. The progressions involve stepping and twisting, opening and closing, bending and straightening. Frantzis had instructed that these exercises should be done until both people's root is so good that the staff breaks. Normally it takes a lot of practice to get that good.
Because I practiced Northern Shaolin since childhood my root was already pretty good when I first tried those exercises, but doing them improved my skill. Anyway, I was showing this football player-student how to do this, with a very strong and flexible staff I might add, and we broke it almost right away. He rooted, I rooted, we moved closer together, the staff bent under enormous pressure and then it snapped.
I was like, okay, you already got that, let's move on to something else. But afterwards it occurred to me that whatever they were teaching him in football training must be a better method for learning rooting.
I started to wonder if Chinese teaching methods were sometimes designed to make the teacher win. As time went by I got really good at teaching rooting to students quickly, I stopped thinking of it as a special skill and assumed my students just had to be encouraged to improve on a skill they already had.
At some point in the last ten years I realized that rooting retards some forms of internal martial arts development. For instance, if you want to be able to force your opponent to carry your whole weight at an angle that will make them collapse, you can't be rooting.
Rooting as a martial arts strategy works just fine. As it does in football. If you want to use pushing or leaning forces, good rooting skills are necessary. But it is mostly incompatible with internal martial arts skills development.