I've worked with systems built upon traditional RCS components that enabled every feature you've described to be applied to any document, regardless of source format, extremely easily. These were internal systems, but they do exist.
I'm not sure if I can believe you. Such a system would have commercial value, and you should be able to refer us to the vendor.
Such a system would also need to have some awareness of the source format to approach the level of detail of change tracking in Office. For example, for ODF and OOXML, the RCS has to know at least to unzip the file and apply diff to the contents inside... and then there would have to be tools to do something with these diffs.
Assuming it can diff two documents, how does a RCS figure out the differences between these two short documents:
These changes take less than a minute to make by a user, and without application-level support, a RCS will just have the state before the user opened the file and after they saved. But integrated change tracking will generate different sequences of events depending on how the user made the change. If they selected the entire line and pasted the new content:
- delete "Today is Friday" at position 0
- insert "today is the day Friday" at position 0
If they made each change individually, this will be reflected in the change history, and the changes will be logged in the order in which they were made, so this is only one of 24 possible sequences:
- delete "t" at position 0
- insert "t" at position 0
- insert "the day " at position 9
- apply italic formatting from position 17-19
A sophisticated RCS with differencing support that was aware of the file format could try to recreate a history like this (by assuming all changes were made from left to right), but can't actually determine the actual sequence and timing of the changes.
The difference seems trivial with a small sentence, but it is a lot more significant when editing a bigger paragraph.