> Python is certainly in the business of trading efficiency and optimal solutions for readability and some notion of simplicity, and that has held it back

Sometimes a simple, suboptimal solution is faster in clock time than an optimal one. You have to write the code and then execute it after all.

As for why ML is dominated by python, I feel like it just gets to the point quicker than other languages. In Java or typescript or even rust there are just too many other things going on. I feel like writing even a basic training loop in Java would be a nightmare.