I agree. But the scientific computing community includes a lot of people who have no exposure to computing at all, so that vectors are copied when passed by value (as opposed to a fat pointer a la Go slices) is a performance foot gun for these new users. For that matter, a lot of people coming to C++ from any higher level language will likely be tripped on on this for a while.
> Mastering C++ isn't even required to be productive using it, since there's no need to use all the language features simply because they exist.
Right, I was distinguishing between "mastering" and "knowing enough to be productive". I'm asserting that you can master Go in far less time than is required to be merely productive in C++ (granted, I'm assuming "productive" means "you're not regularly introducing memory leaks, segfaults, etc" i.e., "you understand memory management best practices in C++"). Specifically, I think it takes 1-2 months for a newbie programmer to become a master of Go and ~6 months to become merely "productive" in C++ (bear in mind that even figuring out how to build non-trivial C++ programs is itself a herculean feat).
Mastering C++ isn't even required to be productive using it, since there's no need to use all the language features simply because they exist. This also avoids the majority of footguns.