If I as a C++ dev come to a new project, I'd much rather that someone was using std::vector or std::array or std::unordered_map or whatever other container beca

If I as a C++ dev come to a new project, I'd much rather that someone was using std::vector or std::array or std::unordered_map or whatever other container because I know how it works, and I know that any other new developer will know how it works. Personally, I would expect very heavy justification (incl. profiling results showing orders of magnitude differences in total task performance) and a very strongly tested + well documented implementation for anyone sending me a PR with their own implementation of a container.