That's the impression I am getting as well. I guess the point of my post is to confirm this and see if there is any work/interest in improving things in this area. While I think the early metadata availability and incremental compilation are all great improvemens, it feels like better parallelization (through more accurate dependency information) is a lower-hanging fruit with potentially more significant benefit, especially if having Multiple libraries in a cargo project becomes reality (I really don't believe manually tracking dependencies between them will scale).
That's pretty much the case for C++ as well, at least where the dependencies are concerned; implementing a conforming preprocessor (which is a minimum requirement for anything general-purpose) is a non-trivial effort.