You are welcome to read up, yourself.
California has constructed dozens of high-altitude, low-head earthen dams on the same principle, over the past century, with penstocks down to lower-altitude turbines, and has lately converted many of them for pumped hydro.
I'm aware of dams. I'm not aware of your fancy alternatives. It is therefore reasonable to assume that those fancy alternatives aren't widely deployed. And that the main reason for this is that they're more expensive (per energy unit).
Without sources, your (admittedly plausible) qualitative arguments are just a pretty story.