For what it’s worth, I do think getting edit notifications would be a valuable future enhancement. Within reason of course. Maybe a couple hours or something like that.
The main use case that I’ve encountered is when you’re asking for help. Someone replies and you read that reply right away. It’s not uncommon for them to edit the reply with more details or clarification, often within minutes of the original reply being posted.
I had a look at this to refresh my memory. Right now, we notify on edit if it’s a new type of notification. That is, if post is edited and a quote is added, a notification is sent. Same thing when adding a link or a mention. (That said, editing multiple times and adding one quote after another will not send multiple notifications. Only the first notification of its type will be sent. See this in post_alerter.rb for context.)
I see this as a feature and not a bug, it’s a compromise between a) not sending any notifications at all on edit and b) sending a notification on every edit.
That said, if we want to stop these quote/link/mention notifications on edit, this would be a good place to do the skipping:
https://github.com/discourse/discourse/blob/master/app/services/post_alerter.rb#L53