Interesting points. Stacked leather would be great at stopping vibration on an impact tool but isn't the best when it comes to long-term survival. It does also tend to dry out and split over time. Maybe it should be looked upon as a temporary/ semi-permanent handle material.
I've yet to meet a person who uses a knife as much as I use my stacked leather grip Estwing hammer and I'm on my second one now*, the few plastic washers that Estwing erroneously think is a good idea failed which ended up causing the handle to rattle.
I keep meaning to repair that first hammer but I don't get the time.
The current one has been out in all weathers, been dropped in a trench full of water various times, fell off the scaffold a few times and all that's happened is the leather has gone a far darker colour**.
I keep seeing pictures of peoples stacked leather gripped knives and to me they've hardly been used or the leather goes very dark. They aren't getting used but there's nothing wrong with the grips as such. Just people being precious I guess.
* Please don't confuse me with a hobby woodworker, its a living, so that hammer gets USED.
** The first thing I did with it was remove the awful varnish they use. It cracks off anyway and I can't stand it.