I recently installed Collabora Online(a packaged version of LibreOffice Online) on my Nextcloud server and it is working fine for basic document editing. And with Nextcloud, I am also able to get comments and chat on the side[2]. Maybe they can integrate this feature more into documents/files.
1. https://www.libreoffice.org/download/libreoffice-online/
2. https://nextcloud.com/blog/nextcloud-introduces-collaborativ...