There is no need to compromise in order to support pre-C++17, you don't need `try_emplace` when the value is like bool and hence doesn't benefit from move seman

There is no need to compromise in order to support pre-C++17, you don't need `try_emplace` when the value is like bool and hence doesn't benefit from move semantics -- plain old `insert` is exactly equivalent, and has existed since std::map's inception.