[rleigh]

As you say, it can't be understated just how much of a conceptual leap git was.

It wasn't developed in a vacuum. And there were several interesting distributed open source version control systems around at the time. After moving on from CVS and Subversion, I tried using Arch (tla) for a project. It was interesting, but still tied to the old way of thinking of version control as a series of deltas, both in its conceptual model and in its storage implementation. In fact, its storage was a tarball of a "base revision" plus a series of patches. Checking out a branch meant unpacking the tarball and applying patches in sequence. It was distributed, and elegant in its own way, but it didn't make the conceptual leap which Linus took with git.

In contrast, the hash-based blob/tree/commit model of git was groundbreaking. The storage doesn't use deltas (except as an implementation detail--as an optimisation in pack files). Deltas are computed on demand. Operations on and synchronising between blob stores is simple and fast. That one change is what made git revolutionary. It opened the door for doing so much more with the version control system.

Still, others took that step around the same time, and the git interface is not what one would call intuitive. But for various reasons it had the momentum and took the crown. It's not perfect, but it's still an absolutely superb tool.