> Git puts a lot of emphasis on maintaining a "clean" check-in history. Extraneous and experimental branches by individual developers often never make it into the main repository. Branches may be rebased before being pushed to make it appear as if development had been linear, or "squashed" to make it appear that multiple commits were made as a single commit. There are other history rewriting mechanisms in Git as well. Git strives to record what the development of a project should have looked like had there been no mistakes.

Right, exactly, because the mistakes often aren't interesting. Where mistakes made in development were interesting, then you should write up the interesting details in you code or commit commentary or other documentation.

> Fossil, in contrast, puts more emphasis on recording exactly what happened, including all of the messy errors, dead-ends, experimental branches, and so forth. One might argue that this makes the history of a Fossil project "messy," but another point of view is that this makes the history "accurate." In actual practice, the superior reporting tools available in Fossil mean that this incidental mess is not a factor.

But that's just so much noise! Some devs will make much more noise than others. Devs who commit often, for example, will make more noise. Noise noise noise. If I'm spelunking through the history I don't want noise -- I want signal. Even if I'm looking through history to find out who is a better developer it may not be helpful because some devs will commit more often.

I mean, why not just record your interactive sessions and then play them back when you want to look at the history? Where would the madness stop?

IMO the madness stops at the upstream, where only linear history should exist.

And again, if I want to look at a project's internal history I can look at their archived clone of the upstream. Even in project "gates" (as we called them at Sun) we kept linear history (some projects had very long history, like ZFS and SMF for example). Very few people looked through archived gates -- I did, from time to time, especially the old SEAM (Kerberized NFS) gates from 1999-2000, but not only. Some archives did get lost -- especially really old ones, the ones that matter more to historians than to current developers, so that sort of loss is a problem, but not one that threatens the ability to do work.