To support this, some wikis will use an imperfect VersionHistory. Old versions will expire from the archive (see KeptPages for an example). If you wrote aggravating stuff in the past, community members cannot easily dig up your statements and remind everybody of your past sins.
There is no guarantee that issues will be forgiven and forgotten, and there is always the outside world to consider: You will leave traces outside the community. There will always be people saving copies of your half-assed remarks somewhere, and putting them on their blogs, and there is the Google cache, and the Internet Archive, just as there are Usenet archives, and log bots on IRC posting the logs on the web... So there is no guarantee that it won't get distributed. On the Internet, everybody does know you are a dog.
The key point is that a technology solution only supports the social convention of forgiving and forgetting. It cannot guarantee it.
See also: DontHateThePlayer
KeptPages hinders forgiveness, because it makes forgiveness irreversible, so people are less likely to practice it. The primary concern should be to get stuff out of the current version, and that seems hard enough already.
The purpose of a FullVersionHistory? is deterrence, not vindictiveness: it leads to a CommunityOfGlassHouses. ForgiveAndForgetInWetware, not ForgiveAndForgetInSoftware. Reliable software histories allow you to defend against ContextSwizzling by allowing you to provide the context in which a comment was made.
For the average reader, the history is worthless gook. However, the HumbleRefactorer? is aided by access to the gook, so that she can fix the current version, so that later readers don't need or want to access the gook. This is almost as effective as auto-deleting the history... perhaps more so, because the existence of the history discourages RecordKeepers.
The social interaction of site archives (the tarball) with KeptPages and ForgiveAndForget is an interesting dynamic. You never know at what point someone has branched the history. It could be--and it seems highly probable that--it might be done in the middle of a FlameWar or a inappropriate personal revelation or some other strangeness that should best be forgotten. But that doesn't mean KeptPages is useless. For a long period it may be that no one will copy the site, in which case the technological forgetting will happen. -- SunirShah