What I don't get is why this:

> rustc is notorious for throwing huge gobs of unoptimized LLVM IR at LLVM and expecting LLVM to optimize it all away.

is seen as a problem with Rust, rather than LLVM. Isn't the whole point of having something like LLVM to have a high-quality backend where all optimizations only have to be implemented once, and then they just light up for all the languages that target it?