I think using git in the background is probably overkill. I don’t need to merge/branch/cherrypick/etc on my blog posts—however, now that I say this, git might be the perfect blogging system since it would be awesome to be able to pull-request factual updates to people’s posts, fork and correct posts, etc. That all could be done without git, but git on the backend might be the simplest way to implement it as a feature while having a lot of prebuilt mechanisms baked in for future features.

However, simply showing and highlighting changes with dates would be great. I often write a post and then an hour later re-read it and decide to clarify something or add more context, and I’d like that history of changes to exist for posterity (and to allow comments to hold contextual relevance in case something changed).