You say that, but look what they are doing with admonitions right now (https://github.com/orgs/github-community/discussions/16925). Despite the RFC (https://talk.commonmark.org/t/generic-directives-plugins-syn...) which is used in a lot of implementations, GitHub decided to do their own thing with an unsemantic, buggy implementation by overloading blockquotes (meanwhile still not supporting admonition styling in reStructuredText or AsciiDoc despite their specs having the feature for years).