One of their requirements is "Based on reusable React Components, it gives developers, authors and designers new ways of working together and creating better and richer experiences more easily."
So basically Prosemirror is not buzzword-compatible enough for them.
And also, "It is built by a company, reducing the likelihood of abandonment." Because Marijn Haverbeke's reputation for abandoning projects is so prominant </sarcasm>
(Full disclosure: I supported the Prosemirror Kickstarter and contributed to CodeMirror.)
Nevermind your sarcasm, but if you'd actually checked out both editors in detail, you would have seen the apparent differences. Anyways, you can replace the standard text editor, which is slate, with prosemirror, as all content is just a plugin.
So basically Prosemirror is not buzzword-compatible enough for them.
And also, "It is built by a company, reducing the likelihood of abandonment." Because Marijn Haverbeke's reputation for abandoning projects is so prominant </sarcasm>
(Full disclosure: I supported the Prosemirror Kickstarter and contributed to CodeMirror.)