Thank you for replying in-depth, I didn't expect it. I actually agree with you re: 2D graphics(I was aware of it already), I just think geometry is different because it has wider applications. Your viewpoint is consistent though.
Again, I think concurrency is one of the parts the standard library does best. (And I think part of the specifics of this is it has primitives like async and future that are higher level and are much easier to explain. I happen to write lock free data structures often enough that finding blog posts at a good level to explain the API for atomic to my code reviewers is a need/bother for me, but there are also plenty of concurrency use cases where I don't need atomics, and I also read that there was a plan to allow parallel execution for most of the algorithms in the standard lib, I don't know if that's in MSVC yet but that's an example of things I like).
I don't blame the standards committee for implementors. In general, it must be terribly difficult to be on the standards committee, and have to deal with stuff implementors have already done, stuff they won't do, and stuff they are telling you they are doing but will not do right in the end. OTOH, as a end user, you have to understand that I have to deal with implementors, and they affect how I think of a given C++ feature, some of which look awesome in the text but are impractical because of implementor differences. I'm not alone: every C++ dev I know has a subset of C++ features they have deemed "practical", based on things like implementation performance, compiler error messages, how many characters the function names have, etc., and part of the problem is it's not the same subset for all C++ devs. Sometimes I wonder if there shouldn't be a subset of the standard (and I don't mean the C subset!) that's earmarked as beginner-safe and compilers could enforce the, well, beginner-safeness of code that is meant to be foolproof... but I suppose your angle is code meant to be foolproof should either never allow a beginner within 50 feet of it or be written in Java (or Rust?). Which, I get.
I would like to clear up a misunderstanding that I think you had: I do not spend zero time learning about C++. I'm not super confident and I think by HN standards I am not very experienced in C++ (or anything else), I'm definitely not at the level where people at CppCon would want me in the room, but people at my workplace do come to me for help with that stuff a bunch of the time. I tend to volunteer to explain newer or more complicated parts, etc. I'm a mid-level dev generally and C++ is my main language, and I'm not significantly more ignorant than my coworkers about it. If that is below the threshold at which you will consider someone worthy of talking about C++ on the Internet, maybe that's why C++ doesn't have that many beginner-friendly communities around.