Collaborative live programming is a pretty bad idea in the first place. There is one thing that's very important that you're missing in your analysis of "the past". All DVCS system allow the programmer to group a set of changes by commits, which constitute a consistent block of changes.

Remove that ability by constantly recording changes, and you can no longer control your code: no code review, no feature merging. Everything just becomes a giant mess. A mess that's auditable, but a mess nontheless