There's no conflict here. You can build it on Git/Mercurial/DARCS/whatever and make it easy for those who are capable to use the command-line or their favorite Git GUI, and at the same time have a visual interface that hides all of that under the cover (e.g. creates a branch when you begin editing). The hard part of this would be conflict resolution, but that's already a hard problem for an online editing system like this (and I didn't look at it long enough to see what the solution here is).