I wish projects had a “what is X” link visible on their sites, or HN had some context text which let posters describe why they posted. (Or the OP post the homepage which had all of this info.)
This is a fork of Wordpress 4.9, for anyone else that didn’t know. I’m not qualified to comment on the reasons why they forked.
WordPress 5.0 introduced the single page react app that is the Block Editor, dropping the tinyMCE editor in December 2018.