> I don't see any major con if it was written in Python
> it would be a tad slower
a tad? I'll use C++ as an example, but the last time I profiled a hash map in C++ vs C#, the C++ lookup took 1 nanosecond[0] and the C# version took 1ms (1000x slower) (I don't have these metrics anymore but I believe it was one ms or slower, and Google seems to confirm that).
Now, if the difference between C++, a machine compiled language, and C#, a runtime compiled language, is 1000x for a very common operation, how much slower will an interpreted language that is running at an even higher level be??
The reason 90% of our apps are such slow trash these days is because programmers think that there is no difference in a couple milliseconds when it is a huge difference if that couple milliseconds is being run thousands of times through hundreds of thousands of lines of code! Take a look at how fast the Jai compiler is compared to a modern C++ compiler. Or even a C compiler vs a C++ compiler. It's night and day because of how much cruft slowly gets added on.
So I find your claim that most of the Unix utilities are only written in C because that was mainstream in the day highly dubious. If anything, they would be written in something like Rust today, but definitely not JS or Python.
Edit: I would also like to point out how much of a pain it would be to write low level network code, like what's necessary in curl, in a language like Python. When you're writing low level net code you want as little interference between the bytes and the programming language. Because if your bytes have some hidden padding, or the endianess is swapped, or a data structure is aligned a byte off, it means the difference between between correct transfer over the net, and sending garbage over the net. Python is not conducive at all to understanding how an object will be transformed into q series of bytes, whereas C is almost a direct translation from a struct to a series of bytes.
[0]: https://gist.github.com/ambrosiogabe/66a6e2fdc77e6a600e570f4...