I agree with much of what you say but as I was thinking about it I thought maybe it is a tell tale of how physically active you generally are.
Studies show that people who sit for extended periods of time have a shorter life expectantly.
So I wonder if non active people could always do it. I think that the more active you are the better your balance. Think Martial Artists.
Short story, I took the whole family, in laws too, to Ormond Beach in Florida one year for a vacation in March before the spring breakers showed up wearing their shoe strings and band aids as bikinis. I had kids. All of us guys went deep sea fishing. Well the seas were 6 foot seas. One boat beside us I heard on the radio had every body puking. Our whole boat was puking except for about 5 of us.
Needles to say when the cut bait came out there was even more hurling. The fishing was terrible. The Captain told me Feb was best.
One kid caught one fish out of 50 people. It Was a party boat. So on the way back in I got tired of hearing people hurl so I went up on the top deck and chatted with the non hurlers up there. We all exchanged names, where we were from etc. one guy was some kind of MD. Neurological of some type. He was asking each one of what we do for a living then explained to each of us why we weren’t see sick. Two guys were linemen buddies, a woman was a fitness instructor and I was a Welder. He continued to explain why each of us didn’t get sea sick.
Mine was because I spent much of my day every day in the dark wearing a welding hood. Many times having to balance a lot to continue and not fall off something while welding especially if there was no hand hold.
The two lineman were self explanatory and the fitness instructor was too.
So it may have to do with a lifestyle where balance is needed. It may have to do with falling a breaking something because of lack of balance when you get older. Thus the importance of staying fit and active.
That’s my take on it anyway. I’m sure there are exceptions to large inactive people that can do the 10 seconds. Not sure
My martial arts friend has been into it since he was 10. He went 71 this May. The horse and cat stance were big in our training venue since 1993. He was flat footed and had more of a shuffle in and out style.
The horse stance can be done like a chair, but works well enough at 45 degrees bent leg instead of 90.
When I started in 1993, I felt like I was a gyroscope in movement. Over the next 20 years I would climb a 155 foot sea cliff, at minimum 4x per week, and run or scramble a 4 mile loop on the rocks of every size and angle.
In all those thousands of runs, I had one bad fall with a twisted ankle; hopping on my left leg off the beach and up the trail at a nearby street park.
With my ankle twice it’s normal size by 18:00 hours, I decided to take 3-grams of curcumin powder, in olive oil with a couple tablespoons of Pinot mixed in around midnight.
Upon waking @ 06:00 I was dumbfounded!
My twice the size ankle was back to normal size, I could walk on it for in the house short distances.
Im no neurologist, but I understand many aspects of how balance and many other attributes are enhanced by exercise that TARGETS THE NERVES!
Unlock those knees and be still and feel the burn.