Another example. I had asked for a TypeTrait is_integer and also supplied code for it (https://github.com/boostorg/type_traits/issues/186). The point is that is_integer only returns integer (no character, no bool). John immediately closed my request "We are not responsible for that".
His response was certainly more nuanced than that. Users are allowed to overload Boost.TypeTraits without it being UB like adding additional overloads in namespace std.
Instead of admitting a mistake (of course I make some myself) and saying "we forgot/didn't think of it, we'll do it", the only answer is "we don't care". That's thinking from the wallpaper to the wall. As I said, boost used to be progressive, but now when you make a suggestion, all you get is "We're not responsible for that/we're not interested in that/we might have to change something that's not possible"
Again, every-time we do not incorporate your suggestions we try and provide you with valid reasoning. Many of the libraries can't advance their language standard because 1 user says so. Since your other emails have been vocal about the supposed deficiencies in Math we don't like to make change for the sake of change. Math is at C++14, and will remain that way for the foreseeable future because that's what our large consumers use.
And this even with such a simple TypeTrait. Single file. No dependencies. And on the other hand, libraries with the most severe buffer overflows (charchonv) are included, where obviously no tests are carried out at all.