> It seems like the velocity of a project is the reciprocal of the number of independent implementations of a spec because any one of the implementations can slow down all the implementations (like what happened with proto3 around required and optional).
Velocity and stability/maturity are in tension, sure. I think for a foundational protocol like protobuf you want the stability and reliability that come from multiple independent implementations more than you want it to be moving fast and breaking things.
Additionally calling C++ from other languages is a pain and you're forced to make a bridge C API. Doing so from Go is even less than ideal from what I gather. It requires using cgo and forces Go to interface with C call stacks, slows down the compilation, etc.
Velocity and stability/maturity are in tension, sure. I think for a foundational protocol like protobuf you want the stability and reliability that come from multiple independent implementations more than you want it to be moving fast and breaking things.