My post was meant as general suggestions of exercises to play with to see what rein holds and hand positions were the most comfortable and effective. I didn’t mean to imply that you ride with piano hands, it was simply another position to play with.
I don’t really care how you hold your reins. It was just an exercise to demonstrate the mechanics behind why most English riders across the globe hold their reins a certain way.
Obviously there will be exceptions. People have different strengths, weaknesses, and conformation. Different rein holds (especially two reins) may be more comfortable or effective on different horses.
And yes it is true that the thumb should be on the reins to secure them. But it’s also true that by having the reins pass through the fingers there is additional leverage. Like a pulley system.