>That's not a "framework" they've been incorporating
What do you call it then?
>What I like about C++ is that it doesn't have, for example, its own GUI or dedicated Database access
Why is this something that you like? This is probably one of the most annoying things there are and at the end of the day developers that need to create a GUI all end up using the same framework, at least if they need portability, so effectively it's the same situation as having an officially supported framework only with downsides.
>How would such a "standard framework" be maintained for potentially hundreds of different computer architectures?
Why of course, the same way your supposedly "well written and documented and straight-forward to use, and well designed to work with different hardware and compilers" software works :^) It's not even about shit code, you could have a solid gold piece of code written by Stroustrup himself and chances are you're going to have a huge headache when you tried to compile it for a different architecture where you couldn't apt-get all the dependencies already compiled and even in the cases I could, I've also encountered problems. It's exasperating and has in several cases resulted in me spending more time debugging build problems than actually doing coding, and I don't think this is acceptable anymore, specially when there are alternatives. And I hate those alternatives for different things, but at some point you just want to cut down on all the bullshit.
I'm aware this isn't really what the language is about, but ultimately I feel unfortunately that's the problem and what's causing it to fade into irrelevancy, at least for non niche jobs. The need to support as many different platforms and hardware configurations is always being reduced given how much hardware has progressed, and unfortunately what a lot of C/C++ jobs have been reduced to is implementing stupid frameworks and middleware for the niggers coding in the higher level languages, while they get to have all the fun implementing the cool business layers.