This is a spitball-level idea I’ve had, and it involves subjects I don’t know a whole lot about. I’ll just toss it out there and see what people think.
Martial arts mystery #1: the Sanchin stance. More generally, any strongly rooted stance where your feet are screwed into the ground, maximizing stability and minimizing mobility. As far as I know, no combat sport uses such a stance: not wrestling, judo, boxing, karate, TKD, Muay Thai, etc. It seems totally dysfunctional from a practical point of view. Why does this stance exist?
Martial arts mystery #2: the shove. Some Chinese styles include powerful shoving techniques. For example, big shoves that send uke flying are a staple of those “internal power” demonstrations for tai chi. Even if you do not believe the demonstration exactly, the technique exists in tai chi. But any time you could shove someone, you could hit them, and it would hurt more. Why would you practice a shove?
A possible clue to solving the mysteries: the lei tai. The lei tai was the traditional location for challenge matches in China. “The lei tai is an elevated fighting arena, without railings, where often fatal weapons and bare-knuckle martial arts tournaments were once held…. Fighters would lose if they surrendered, were incapacitated, were thrown or otherwise forced from the stage. The winner would remain on the stage (as its "owner") unless ousted by a stronger opponent. If there were no more challengers, they would become the champion.” (Wikipedia)
The final fight scene in the first Ip Man movie is on a leitai.
So here is my speculative guess. Suppose you are a martial arts master in old China. You know that you or your students are going to have to fight, at some point, on a lei tai. You win if you can knock your opponent off; you lose if you get knocked off; and some of those platforms are really high, so falling off is no joke. In that situation, (1) powerful shoves might be preferred to strikes. And (2) you could use a strongly rooted stance as shove defense, to prevent getting shoved off yourself.
If that were right, you could predict:
1. Shoving techniques, and rooted stances, would not be found (or die out) in places with no leitai. Like Okinawa for example. I think this is true: the older Matsumora lineage of karate has a lot less of the rooted stances than the newer Goju lineage, for example. And you don’t find this in Korea. I don’t know whether you could distinguish different regions of China in this regard.
2. You would expect shoving techniques, and rooted stances, to be found in the same systems. I’m not sure this is true. Does anyone know?
OK, like I said, that is just a wild guess. What do people think?