Back when Rust was announced, it was much more similar to Go than it is now, even having a similar runtime for concurrency. Go did a better job than Rust of delivering this paradigm, largely because the Go implementors weren't relying on commodity technologies like LLVM and libuv.
As time went on, Rust was given more support by Mozilla, and it evolved into something more suited for browser implementation. It had other major influences at this point:
- The constraints of using LLVM. Many projects have failed trying to make LLVM do something that it's bad at doing. At the end of the day, LLVM is good at compiling C++ and things that look like C++, so if you stick to using LLVM and want an efficient language, your language will end up looking more like C++ over time.
- The swell of momentum around C++11. All of a sudden, programming idioms from the "Modern C++" movement were becoming mainstream.
- The halo of academic research into type-safe systems languages. Very few of the ideas in Rust are new, but some type system features from academia became more palatable for ordinary programmers when combined with the C++11 style.