And, perhaps most significantly, there are a wealth of C++ libraries out there that have no equivalent in other languages, and being able to use them is an education in itself.
So, learning to code professional C++ will not help you understand machines more. You'd have to learn C, basic OS/CPU structures, and which compilers produce for certain C statements. Maybe read Write Great Code by Hyde or some online articles. Learn C++ to understand machines? Not happening unless you microprogram a CPU for it on a FPGA.
If you want to understand what is actually happening on the machine, I do not think it is the best choice. C would be much better.
Given that you didn't answer the question, I think it's pretty clear at this point that you haven't used Rust. Rust is a low-level language with low-level control over memory and resources.
Variadic generics and template templates are hardly interesting compared to concepts, pattern matching, and lifetimes. I use those every day in Rust, they simply don't exist in C++, and with the exception of lifetimes plenty of other languages have them too, so they're broadly useful to know. Variadic generics and template templates, on the other hand, are useful for a small subset of advanced library authors who have been programming in C++ for years.
The original assertion was:
> ...gives a developer more insight into the actual machine...
For better or worse, Rust feels like a reference is a proper abstraction over a memory location whereas C drives home that it really is just a number. Perhaps I don't know Rust well enough but, without unsafe, I'm not sure how I would refer to an arbitrary memory location or use pointer arithmetic to access memory locations relative to a known memory location in Rust. Vector indexes in Rust appear to be more than just syntax sugar for addition whereas C allows both array[2] and 2[array]. And I know that Rust will prevent me from accessing memory that's already been freed since it's one of the selling points of the language.
Now you can argue that Rust is mostly saving you from unpleasant consequences, and you'd be right. But the fact that C forces you to understand those unpleasant consequences teaches you something about the nature of the underlying machine. C makes you realize just how much of a "wild west" situation exists at that level. It would be very easy for someone to learn Rust without being confronted with that fact.