People not using the latest Standard are waiting for support within their particular environment, not because they want to stay with a less performant version of the language.

But this is what you said:

> Failing to use the new feature is just failing to write code the best way that is available right now. In 2013 you had no choice but to do it the old way; but you don't have to anymore, because the language and std library have caught up with you.

What I hear you saying is that failing to use new features is a failure to write the best code available, and that before maybe you didn't have a choice but not anymore.

And yet, huge chunk of C++ devs are forbidden by their organizations from using various C++ features that have been added throughout the years. It's not just C++ 17 but it goes back even further. This is the whole point of TFA. So it's not just that people are "waiting" for tools to catch up, unless you have evidence of this.

Organizational inertia is a problem, but not a problem that a language or Standard can fix.

When an organizational logjam is broken, programmers can immediately switch over to the better, more modern way of coding enabled by the newer Standard they are allowed to use. If they were on C++98, and now they can use C++14, they are still better off than before, even if the current Standard is C++20: they will be able to code according to best practices for C++14, which are better than for C++98.