I think most people would love to the know the 'why'. This page discusses differences with prosemirror and is the closest I got to that question: (https://wordgard.net/docs/prosemirror/).
One thing to note is that there is not an upgrade path. Many concepts are shared with prosemirror, but it seems that switching means doing quite some work (correct me if I am wrong). Obsidian is based on Code Mirror so I guess they won't be switching, but tiptap.dev and others do.
@marijn, maybe you could address why wordgard is worth the switching cost?
One thing to note is that there is not an upgrade path. Many concepts are shared with prosemirror, but it seems that switching means doing quite some work (correct me if I am wrong). Obsidian is based on Code Mirror so I guess they won't be switching, but tiptap.dev and others do.
@marijn, maybe you could address why wordgard is worth the switching cost?
EDIT: I see many points are addressed in Marijn's personal blog. I submitted (https://marijnhaverbeke.nl/blog/wordgard-0.1.html) to HN for better context.