It was certainly not a remarkable improvement in the sense of being memory safe even in the face of race conditions. As the article points out, Java and C# both managed to do that, and both predate Go.
I'm certainly not disagreeing, but I will note that by definition, most people are in the mainstream, so something being a remarkable improvement over what came before (in the mainstream) is a remarkable improvement (for most people).
Basically go was designed ignoring all the research and progress that had been made in programming languages until then.
It was designed with contempt for developers, for example disallowing developers to create generic data structures, or lacking a decent way of error checking that is not extremely error prone and verbose.