That's going to be the case regardless. If you compile to x86 machine code you're standing on a huge black box, but this time it's also an ugly, platform specif

That's going to be the case regardless. If you compile to x86 machine code you're standing on a huge black box, but this time it's also an ugly, platform specific one. You think people should rather worry about getting lexical scope right, then why should they worry about the low level details? Sure, they have to have at least some idea about how it works on the lowest level, but they don't have to know all the stupid man-given details. Choosing LLVM over x86 assembly is good for performance and productivity. Performance with LLVM will be better unless you are going to spend an extraordinary amount of time to build better low level optimizations, register allocation and code generation than LLVM.