There are a lot of features which a markdown editor can have which are somewhat difficult to implement and get right, such as WYSIWYG with css theming, support

There are a lot of features which a markdown editor can have which are somewhat difficult to implement and get right, such as WYSIWYG with css theming, support for latex equations, support for nonstandard features like Pandoc markdown, plugins, support for the textbundle format... Nothing exists that implement these perfectly and so I think people make attempts at making something that at least works for their specific use case but no one can make the one true editor that does everything because it would be a huge amount of work.