Yes, but it would be just as easy to write an "assembly compiler" that did the same optimizations on your program text. C provides a layer above the machine that acts as we imagine a machine to work; the compiler adjusts our expectation to reality.
In the end, C has branching and memory access, and that's basically what our computers have too. The rest is details.
> Yes, but it would be just as easy to write an "assembly compiler" that did the same optimizations on your program text.
While there are ways to optimize machine code without extra debug information, no, what you've said is not true. It is not nearly as easy to optimize machine code as it is to optimize C.
In the end, C has branching and memory access, and that's basically what our computers have too. The rest is details.