I don't understand the question. I wouldn't say having a GC is the most important facet--I'd rather have good tooling and ecosystem. Of the mainstream languages without GCs, Rust is the only one with good tooling and ecosystem (or arguable C/C++ have "good ecosystem" but the tooling makes it prohibitively difficult to integrate well). Further, the other GC-less languages have a lot of other issues, such as poor error messages and bad ergonomics. Basically success correlates with having a GC, but this is a classic case of correlation != causation.