How many hours would you expect that rewrite to take when done by Python developers learning Rust as they do it?
And what's the opportunity cost of the new features they can't create because they're rewriting existing apps?
If you're arguing that Python has more runtime overhead than Rust, I don't disagree.
But there's a reason people invented higher level languages than C. Rust is a far nicer systems language than C, but is it faster to develop in than Python or Kotlin? It really depends.
I think the argument of the article is to pick the right language in the beginning so you save both developer time and runtime and don't have to rewrite in a better language later. For example, Python is a lot slower than threaded C, but quicker in terms of developer time and is memory-safe. If you pick one of the newer JVM languages though, you can get far closer to C than Python in performance once the JVM is running and still keep most of the expressiveness.
The reason I’m mentioning Rust is because you can still build your fun part of your application in python, and easily use the FFI to build any performance-critical part in Rust, C or C++.
That said, with Rust or C++ you can – depending on the situation – be clearly as effective, or even more effective than with Python, and you gain an enormous performance benefit (which in turn saves you money, which in turn means you can hire even more developers)
It is not clear that Rust can be as fast to develop in as Python or Kotlin, for the typical run of coders--people using Rust now are mostly well above average--but it is abundantly clear that, supported by good libraries, modern C++ can. Faster would be a tall order, but is not necessary.
Put in the same effort, and get 10x-1000x faster code or lower resource needs. Why not?
And what's the opportunity cost of the new features they can't create because they're rewriting existing apps?
If you're arguing that Python has more runtime overhead than Rust, I don't disagree.
But there's a reason people invented higher level languages than C. Rust is a far nicer systems language than C, but is it faster to develop in than Python or Kotlin? It really depends.