The difference is culture and tooling: linking against random .so files is normal in the C world, while Rust strongly encourages you to use source dependencies.
For the time being, as Apple showed by their gigantic effort with Swift ABI, there are C and C++ shops (and Objective-C ones) that really care about dynamic libraries, which any alternative needs to take into account for their adoption.
The main issue is the culture, being more in line with ALGOL/PL/Ada/Wirth languages point of view of why security matters, even if there is a bit of unsafe core around.
