But how many want to link the Go runtime into their program? Maybe they just don't want it there, or maybe they already have other runtimes linked in their prog

But how many want to link the Go runtime into their program? Maybe they just don't want it there, or maybe they already have other runtimes linked in their program and don't want one more, or maybe they have runtime version conflicts, etc. Also, such interfaces generally require more copying around of structures to match the format the language is expecting. With rust, it can use plain C structs directly without translation.