Maybe it's ADHD, but I see the use for edit. The number of times I post something then realise I forgot to articulate a key point.
As long as it's obvious an edit has been made and the history readable, it's not really white washing.
Delete is a bigger problem, but it wouldn't be hard to run relays that don't honour delete to archive notes, particularly of important accounts.
I don't think we will see lots of grammar Nazis trying to polish everyone's notes. Edit allows collaboration, which has its place.