I think its probably that Go was being worked on by Google employees and the fact that GC languages were well accepted. A lot of early converts to Go were Python programmers, C++ devs didnt jump ship to anything else until Rust, I am seeing plenty of places integrating Rust with C++ code in some cases for mission critical code. I mean just look at when Discord switched from Go to Rust. They also used Rust to aide their BEAM VM code.

Yeah, this matches up more with my observations as well. Go's niche is mostly in modern deployment/infrastructure management and web backends, places that historically Python might've been the premier choice.

Rust gives you better insight and control over memory management that is necessary for many of the applications that are written in C++ while offering strictly better safety guarantees and less baggage (but the tradeoff of encoding a lot of stuff in the type system). I really like Go, Rust, and Python, but all for different things.

I always thought of D as a better C++, not a better C. But at the time D showed up, C++ still showed some promise (in that sense it is right that D might have been too early, the C++ fatique hadn't set in yet for most C++ users, so why switch to D).

Maybe there is a little of that, but I think it was largely the D compiler's weird source-available licensing.

Lots of people were using C++ and were not happy with it.