This looks very interesting but I doubt large enterprises will allow it considering the online nature and the inability to secure confidential work on internally hosted systems.
I'd be happier with something that simply allows me to have a github-like workflow where I can propose and justify changes to this or that block of document, and an owner can sanction and merge. This would not touch internal hierarchies (the most sacred element of corporate life) but would improve collaboration.
If Fluid is a step in that direction, it's welcome. Unfortunately to me it looks more like "web-native COM objects" and few people ever liked those.
This is called 'Tracked Changes' and 'Comments' in Word. Under the Review ribbon.
Here's the How-To: https://support.office.com/en-gb/article/track-changes-in-wo...
Absolutely not comparable to a github experience, as far as I can see.