> On the contrary, I think 80%+ of the language is accessible to every programmer.
80% of the language looks accessible to every programmer. Until you hit some corner of C++ behaviour and you realize your mental model of what C++ is doing is woefully incomplete. C++ is stuffed full of syntax, and obscure interactions between that syntax will continually trip you up. Each of the things in your list is somewhat contained on its own but interacts in surprising ways with every other thing on that list.
For example[1], want to create a template friend function for a template class? Prepare for function definitions like:
Foo<T> f<>();
Edit: that's not to mention various C++ idioms like CRTP [2] which don't fit neatly with the stuff you listed but are non-obvious and occur in a lot of complex C++ code.
I am saying one can barely write programs by knowing just 25% of C++, let alone for almost two decades.
On the contrary, I think 80%+ of the language is accessible to every programmer.