The point is not about relying on C/C++, it's about using existing implementations instead of re-inventing the wheel all the time. This is a cultural thing when it comes to Go and it has bitten them multiple times, like when they tried not to use the system's libc on MacOS or when they had issues when dealing with memory pages on Linux.

Good to know there's someone in charge specifically of the cryptographic stuff for Go at Google though.