I am still not understanding what the abuse would be ??
People editing offers after the fact ??
Maybe I am a stupid trusting person but I do consider even a typed private conversation to be a extension of "My Word Is My Bond"
Frannie
Trusting yes but stupid? Never.

I always liked to give members the benefit of the doubt, but I can't tell you how many times my trusting side has been bit in the ass over the years.
But when someone has been in the game as long as I have (I date back to being a sysop on Compuserve, before the web became popular), let's just say I've seen
everything.
In a forum post, a couple of things can happen. I had forums where editing was something you could turn on, or off...no time restriction when it was on. I had a couple of members come along and decide they didn't want an account anymore, so they'd go and edit every single post, emptying it completely. So it ruined dozens of threads. With a time limit, that prevents someone from doing that after the fact. (But now, with the edit history and the ability to restore any version of a post with a single click, it's an annoyance that can be recovered from...it just creates a huge amount of unnecessary work for the staffer who has to do it.)
And there are cases I have in a larger forum where one member will take a shot at another, leave it up for 14 minutes, then edit out the nastiness before our 15 minute time limit elapses, knowing the target member of the abuse has read it (as we often get the report). Many don't realize we have an edit history and can read every version of the post.

Yet they think they can get away with it.
In conversations, I'm torn. I like being able to clean up my sloppy typing, but on the other hand, having that message "set in stone" to avoid abuse is almost a necessity for the few that might abuse it.
We'd all like to leave unlimited editing and deletion abilities intact, but those 0.1% of users ruin it for 99.9% of the others. Lessons learned, I guess.