Why are edit revisions visible?

I must admit to getting a little lost regarding the more abstract theory behind comment systems, and the minutia of their management. This might explain why I’m not grokking the net benefit of fully visible edits records. Perhaps if @sam or @codinghorror could translate from the original G[r]eek for us layfolk, I would be able to grasp it? Not being sarcastic, just not a programmer/designer, and therefore need a more detailed explanation-for-dummies as to how

mountains of weird can happen.

(Um, “edit”: is the concern that people will quote pre-edit posts, thus causing confusion? I don’t think this has ever confused me very much. And when it does, a simple edit notification on the quoted post is sufficient to let me know that a change has been made. The outdated quote “tracks the changes” quite efficiently; it is different than what is in the quoted comment now, so it’s easy to deduce the editing process.)

It strikes this kinda-dummy that any mountains of weird are more likely to arise from people digging around to find “embarrassing” pre-edit tidbits, if anything. I guess I could see how reading a pre-edit version might help flesh out where a fellow poster is coming from, or trying to go, but mostly it just seems like an invitation to suspicion and potentially confusing references. To be clear, I don’t mind that people know I edit many of my posts. Like @Donald_Petersen, I tend to go long/wordy, and that approach frequently requires edits. Whatever; I put some effort into thinking through a post and revising it for clarity, and I don’t care if people know it. That said, showing the entire sausage making process seems unnecessary,a little invasive, and potentially problematic.

Related question: I recently noticed that one of my comments had been edited. Yes, probably by me, but more recently by @codinghorror. I read the whole thing in the edit history window, and couldn’t figure out what had been changed, or why a mod-type person was editing my posts. I’m not at all trying to get mountainously weird about it, but what happened there, anyway?