If I recall, Golang was made to make fresh college graduates more productive. I don't know if large C++ code bases are a good place to get junior devs started, there's quite a risk that they'll introduce subtle bugs because of C++'s... C++-ness if you don't give them an in-depth course before putting them to serious work. C++ and Go are languages with different stengths, purposes, and use cases.
Golang only accepts one way of doing things and it looks like Python. It makes assumptions to replace complexity so you don't need to think too deeply in many cases. I would never pick it for any serious project, but as a quick one-off tool, especially if you're planning on networking it, Go can get the job done easily and painlessly enough.
Now, Dart, on the other hand, that's a language that doesn't need to exist in my opinion. It's ES5/ES6 with some tweaks but IMO TypeScript has since easily surpassed it at a language level. I don't know why Dart still exists, but we're stuck with it now that Flutter uses it.
It was made by veteran SWEs frustrated with C++ in whatever level of code that it was too pedantic for. I think it was targeting all that stuff that was written in C++ rather than Java for performance reasons but could still use bounds checking and GC. Pretty specific use case. Java, Python, or JS will still be a lot quicker to work with for higher-level things or quick scripts.
