Scalar replacements (as currently implemented in Java) does not work in real-world programs.

Well-written code does not need it. Poorly written code can not trigger it, because the JIT is too dumb and isn't getting better.

There is no sane test to determine whether a piece of code will be inlined in Java. In practice anything more complex than byte array is unlikely to be inlined. Even built-in ByteBuffers aren't! Meanwhile Go compiler treats Go slices just as nicely or better than arrays.